Genetic causes such as Turner syndrome have initial ovarian development but then ovaries degenerate rapidly during prenatal life, often leading to gonadal dysgenesis with streak ovaries. In those cases where POI is associated with adrenal autoimmunity, histological examination almost always confirms the presence of an autoimmune oophoritis in which follicles are infiltrated by lymphocytes, plasma cells, and macrophages that attack mainly steroid-producing cells and eventually result in follicular depletion. [ 15 ]


In some women FSH may bind to the FSH receptor site, but be inactive. By lowering the endogenous FSH levels with  ethinylestradiol  (EE) or with a GnRH-a the receptor sites are free and treatment with exogenous recombinant FSH activates the receptors and normal follicle growth and ovulation can occur. [ 23 ] [ 24 ]  (Since the serum  Anti-Müllerian hormone  (AMH) level is correlated with the number of remaining primordial follicles some researchers believe the above two phenotypes can be distinguished by measuring serum AMH levels. [ 25 ]


Genetic associations include genetic disorders, [ 8 ]  autoimmune diseases, [ 3 ]  enzyme defects, [ 15 ]  and resistant ovaries. [ 8 ]


Mutations in FOXL2 cause  blepharophimosis, ptosis, epicanthus inversus syndrome  (BPES). Premature ovarian failure is part of the BPES Type I variant of the syndrome but not of the BPES Type II variant. [ 26 ]


BRCA1  protein plays an essential role in the repair of DNA double-strand breaks by  homologous recombination . Women with a  germline  BRCA1 mutation tend to have premature menopause as evidenced by the final amenorrhea appearing at a younger age. [ 27 ]  BRCA1 mutations are associated with occult POI. [ 28 ]  Impairment of the repair of DNA double-strand breaks due to a BRCA1 defect leads to premature ovarian aging in both mice and humans. [ 29 ]


In addition to BRCA1, the  MCM8 -MCM9 protein complex also plays a crucial role in the recombinational repair of DNA double-strand breaks. [ 30 ]  In humans, an MCM8 mutation can give rise to premature ovarian failure, as well as  chromosomal instability . [ 31 ]  MCM9, as well as MCM8, mutations are also associated with ovarian failure and  chromosomal instability . [ 32 ] [ 33 ]  The MCM8-MCM9 complex is likely required for the  homologous recombinational  repair of DNA double-strand breaks that are present during the pachytene stage of  meiosis  I. In women  homozygous  for MCM8 or MCM9 mutations, failure to repair breaks apparently leads to  oocyte  death and small or absent  ovaries . [ 31 ] [ 32 ]


The diagnosis is based on age less than forty, amenorrhea, and two elevated serum  follicle-stimulating hormone  (FSH) and decreased  estrogen  measurements at one-month intervals. [ 10 ]  The anterior pituitary secretes FSH and LH at high levels to try to increase the low estrogen levels that are due to the dysfunction of the ovaries. Typical FSH in POI patients is over 40 mlU/ml (post-menopausal range). [ 2 ]  The evaluation of amenorrhea for other common causes includes checking a blood  pregnancy test , checking the  prolactin  level, as  prolactinomas  or certain medications can increase prolactin levels and lead to amenorrhea, and checking the  thyrotropin  (thyroid hormone) level, as  hypothyroidism  can cause amenorrhea. [ 10 ]  A karyotype (to evaluate for  Turner's Syndrome ) and a Fragile-X premutation carrier analysis is also recommended, with additional  genetic testing  possibly being warranted based on family history of amenorrhea or early menopause or signs and symptoms of a genetic disorder. [ 10 ]


Between 5 and 10 percent of women with POI may become pregnant with no treatment. [ 12 ]  As of 2016 no fertility treatment has been found to effectively increase fertility in women with POI, and the use of donor eggs with  in-vitro fertilization  (IVF) and adoption are a means of achieving parenthood for women with POI. [ 13 ]  Some women with POI choose to live child-free. [ 14 ]


Researchers have investigated the use of a hormone called  dehydroepiandrosterone  (DHEA) in women with POI to increase spontaneous pregnancy rates. [ 34 ] [ 35 ]  Results from studies on DHEA in 2010 indicated that DHEA may increase spontaneously conceived pregnancies, decrease spontaneous miscarriage rates and improve IVF success rates in women with POI. [ 36 ]  This includes women referred for donor eggs or surrogacy in 2009. [ 37 ]  In 2018, there was no significant improvement in ovarian function by 12-month on DHEA supplementation in women with POI. [ 35 ]  Given the inconclusiveness of potential benefits and risks of testosterone and DHEA supplementation, longer-term, randomized studies are warranted for women and girls with POI. [ 38 ]


Ovarian tissue cryopreservation  can be performed on prepubertal girls at risk for premature ovarian failure, and this procedure is as feasible and safe as comparable operative procedures in children. [ 39 ]


In 2013, Kawamura in Japan and his collaborators at Stanford University published treatment of infertility of POI patients by fragmenting ovaries followed by in vitro treatment of ovarian fragments with phosphatidylinositol-3 kinase activators to enhance the AKT pathway followed by autografting. They successfully promoted follicle growth, retrieved mature oocytes, and performed in vitro fertilization. Following embryo transfer, a healthy baby was delivered. [ 40 ] [ 41 ]  A  2020 review covered variations including phosphatidylinositol-3 kinase activators to enhance the AKT pathway, fragmentation of ovarian cortex, combining those two into in-vitro activation (IVA), and drug-free IVA. Two laparoscopies are needed in conventional IVA and one with drug-free IVA. [ 40 ]


Women with POI can develop symptoms of estrogen deficiency, including  vasomotor flushes  and vaginal dryness that respond to physiologic replacement of hormones. [ 9 ] [ 4 ]  Most authorities recommend that this hormone replacement continue until age 50 years, the normal age of menopause. The leading hormone replacement regimen recommended involves the administration of estradiol daily by either skin patch or vaginal ring. This approach reduces the risk of  pulmonary embolism  and deep venous thrombosis by avoiding the first pass effect on the liver that is induced by oral estrogen therapy. [ 4 ] [ 42 ]   The transdermal estradiol patch also provides the replacement by steady infusion rather than by bolus when taking daily pills. [ 42 ]


Concerns of estrogen supplement are addressed in The US Medical Eligibility Criteria for Contraceptive Use, 2010 provides guidance for safety of contraceptive methods and include guidance for conditions associated with increased risk of thrombosis such as postpartum, history of thrombosis, thrombogenic mutations,  systemic lupus erythematosus ,  diabetes , and hypertension. [ 43 ]  There is also an increased risk with valvular heart disease and  cardiomyopathy . [ 44 ]


To avoid the development of  endometrial cancer  young women taking estradiol replacement need also to take a  progestin  in a regular cyclic fashion. The most evidence supports the use of medroxyprogesterone acetate per day for days one through 12 of each calendar month. This will induce regular and predictable menstrual cycles. It is important that women taking this regimen keep a menstrual calendar. If the next expected menses is late it is important to get a pregnancy test. It this is positive, the woman should stop taking the hormone replacement. Approximately 5 to 10% of women with confirmed POI conceive a pregnancy after the diagnosis without medical intervention. [ 4 ]


In observational studies, hormone replacement therapy in women with primary ovarian insufficiency and other causes of early menopause was associated with a lower risk of  cardiovascular disease , increased  bone density , and a reduced mortality. [ 10 ]


Primary ovarian insufficiency is associated with co-morbidities associated with menopause including  osteoporosis  (decreased bone density), which affects almost all women with POI due to an insufficiency of  estrogen . There is also an increased risk of  heart disease , [ 8 ]   hypothyroidism  such as  Hashimoto's thyroiditis ,  Addison's disease , and other autoimmune disorders. [ 45 ]


The most common words women use to describe how they felt in the two hours after being given the diagnosis of POI are "devastated", "shocked," and "confused." [ 1 ] [ 46 ]   The diagnosis is more than  infertility  and affects a woman's physical and emotional well-being. [ 4 ]  Patients face the acute shock of the diagnosis, associated  stigma  of infertility,  grief  from the death of dreams,  anxiety  and  depression  from the disruption of life plans, confusion around the cause, shame, insecurity and lowered self-esteem, anger in reflection of being letdown by the medical system, symptoms of estrogen deficiency, worry over the associated potential medical sequelae such as  reduced bone density  and  cardiovascular risk , and the uncertain future that all of these factors create. [ 1 ] [ 4 ] [ 6 ]  Women diagnosed with POI in their 20s have disproportionately reported experiencing dismissiveness, bias, and "not being taken seriously" by healthcare professionals. [ 47 ]


Some have advocated formation of a patient registry as well as a community-based research consortium with integrative care to better understand the etiology and treatment of the condition, including treatment of its psychological effects. [ 7 ]  Women with POI perceive lower social support than control women, so building a trusted community of practice for them would be expected to improve their well-being. Also, when having that social support, it often helps with reducing stress and having better coping skills. [ 47 ] [ 48 ] [ 49 ] [ 50 ]  It is important to connect women with POI to an appropriate  collaborative care team  because the condition has been clearly associated with suicide related to the stigma of infertility. [ 49 ]   Suicide  rates are known to be increased in women who experience infertility. [ 51 ]


The prevalence increases with age and is approximately 1 in 10,000 women under age 20, 1 in 1,000 women under age 30, and one percent by age of 40. [ 6 ] [ 52 ]  It occurs in 3.7% of women worldwide and 1% of women in the United States. In the United States, the incidence is 1% in White women, 1.4% in Black and Hispanic women, with lower rates seen in Chinese and Japanese women, at 0.5% and 0.1% respectively. [ 10 ]


Fuller Albright  et al. in 1942 reported a syndrome with amenorrhea, estrogen deficiency, menopausal FSH levels, and short stature. They used the term "primary ovarian insufficiency" to distinguished POI from ovarian insufficiency secondary to a primary failure of  pituitary  FSH and other hormonal secretion. [ 53 ] [ 54 ]  POI has been described as a more accurate and less stigmatizing term than premature ovarian failure [ 4 ]  or premature menopause. [ 4 ] [ 11 ]


Chapter 28 of the early  Qing dynasty  work  Fù Qīngzhǔ Nǚkē  (《傅青主女科》 Fù Qīngzhǔ's Gynecology ) describes the cause and appropriate treatment for premature menopause. 年未老经水断 (niánwèilǎo jīngshuǐduàn) glosses as 'not yet old, menstrual water cut-off.' [ 55 ]


The  timing hypothesis ,  gap hypothesis ,  gap theory , or  critical window hypothesis   for menopausal hormone therapy  is a  scientific theory  that the benefits and risks of  menopausal hormone therapy  vary depending on the amount of time a woman has been in  menopause  upon initiation of treatment. [ 1 ] [ 2 ] [ 3 ] [ 4 ] [ 5 ]  More specifically, it is thought that hormone therapy may be protective against  coronary heart disease  in women who initiate it in early menopause but may be harmful in women who start it in late menopause. [ 1 ] [ 2 ] [ 3 ] [ 4 ]  The timing hypothesis may also extend to risks of  breast cancer [ 6 ] [ 7 ] [ 8 ] [ 9 ]  and  dementia  with hormone therapy. [ 10 ] [ 11 ] [ 12 ] [ 13 ]  It is thought that the increase in breast cancer risk may be greater in women who start hormone therapy in early menopause but may be lower or that even decreased risk of breast cancer may occur in women who start in late menopause. [ 6 ] [ 7 ] [ 8 ] [ 9 ]  The influence of hormone therapy on  depressive  symptoms may additionally be influenced by menopausal stage, with significant benefit seen in  perimenopausal  women but not in  postmenopausal  women. [ 14 ] [ 15 ] [ 16 ] [ 17 ] [ 18 ] [ 19 ]  The timing hypothesis is potentially able to resolve conflicting findings between large  observational studies  and  randomized controlled trials  on long-term health outcomes with menopausal hormone therapy. [ 1 ] [ 2 ] [ 4 ] [ 8 ] [ 9 ] [ 20 ] [ 21 ]


Wulf H. Utian  is a physician, reproductive endocrinologist, clinical researcher, and academic women's health department administrator. He is best known for first recognizing  menopause  as a potential health-related issue. He is the co-founder of the  International Menopause Society  and founder of the  North American Menopause Society . Previously he has worked as a medical department Director at the  Mount Sinai Medical Center , the  University Hospitals of Cleveland , and academic chairman of the department of Reproductive Biology at Case Western Reserve University School of Medicine. He is currently the Arthur H. Bill Professor Emeritus of Reproductive Biology at the  Case Western Reserve University School of Medicine , a consultant in women's health, and Scientific Director Emeritus of Rapid Medical Research Inc. [ 1 ]


Utian received an MD from the  University of the Witwatersrand  and a PhD from the  University of Cape Town . He also received a DSc degree in medicine in 2007, becoming only the eleventh recipient of the degree in 100 years. [ 2 ]


Utian is credited for describing menopause as a potential health-related issue in 1967. He has described the situation that led to his discovery as occurring when he was invited to visit a large pharmaceutical firm in  West Berlin . He has stated that "A new female hormone was mentioned and thereby started my interest in the subject. Upon my return [home] I approached the Chairman of the Department of Gynaecology of the University of Cape Town ... and spelled out my plans for a menopause clinic." This clinic, named the Femininity Clinic (later renamed the Mature Woman Clinic), was the first of its kind in the world, located at the  Groote Schuur Hospital . [ 3 ]  In 1976 he also became one of the three co-founders of the  International Menopause Society . [ 2 ]  Utian ultimately left South Africa due to conflicts with the  Apartheid government , including his objections to the treatment of non-white physicians in the country's hospitals. [ 4 ]


Utian ran the South African clinic until his move to Cleveland Ohio [ 3 ]  in 1976, [ 5 ]  where he began to work for the  University Hospitals of Cleveland and Case Western Reserve University School of Medicine . [ 3 ]  He then served as Director of Obstetrics and Gynaecology at the Mount Sinai Hospital of Cleveland. In 1982 he began performing  In vitro fertilisations , becoming one of the first medical doctors in the US to do so. [ 6 ]


In 1985 he became the first physician to successfully complete the in vitro fertilization of a surrogate mother without using an egg from the surrogate mother. Utian's team instead removed eggs from the ovaries of a woman whose uterus had been removed, fertilized them with her husband's sperm, and implanted the fertilized eggs into the womb of a surrogate mother. Utian reported the event to the  New England Journal of Medicine  in a published letter announcing it as the world's first successful effort of this kind. All previous surrogate pregnancies had used an egg from the surrogate mother instead of the woman unable to have children. [ 7 ]  The baby was also the world's first baby where a court in Michigan determined that the genetic mother and not the birth mother was the one who should be listed on the birth certificate (the first baby in the world where the women who gave birth was not recognized as the mother). The story was featured on the cover of  Life  magazine and on  Nova . [ 8 ] [ 9 ]


Utian became the Director of the Department of Obstetrics and Gynaecology at the University Hospitals of Cleveland and Chairman of Reproductive Biology at Case Western Reserve University in 1989, [ 10 ]  staying in the position until 1999. [ 11 ]  In 1989 Utian also became the Executive director and founder of the  North American Menopause Society , located in  Cleveland, Ohio . [ 12 ]  He also served as the editor of the society's scientific journal  Menopause . [ 13 ]  He has additionally served as the President of the  International Menopause Society . [ 14 ]  In 1998 he became the founding Secretary of the Council of Affiliated Menopause Societies. [ 15 ]  Utian retired from the head of the North American Menopause Society in 2009. [ 16 ]


Utian left academic department administration after twenty years service to continue as a medical practitioner at the  Cleveland Clinic , and clinical research scientist at Rapid Medical Research, which he founded in 1997. [ 11 ] [ 17 ]  He also served as a professor of obstetrics and gynaecology at Case Western Reserve University, [ 18 ]  where he is now Arthur H. Bill Professor Emeritus of Reproductive Biology. [ 2 ]  Utian served as the Medical Editor of  Maturitas  from 1983-1993, was named Honorary Founding Editor of  Menopause  (1994-2010), and served as Editor of  Menopause Management  between 1987 and 2009. [ 19 ] [ 20 ]


In 1976 Utian co-determined the first internationally accepted definitions of menopause and time-related events.
In 1985 Utian publicly disagreed with the medical definition of menopause agreed upon by the International Menopause Society. He believed menopause to be a potential endocrinopathy (disease of the endocrine system), with potential adverse physical effects on pelvic and extra-pelvic organs such as bone, cardiovascular system, brain, skin and sensory organs. [ 21 ]  He has written that menopause has been recognized by society as a stage of life as far back as Biblical times. [ 22 ]  Utian has stated that the symptoms women experience when their ovaries shut down are due to an evolutionary lag, as the endocrine system of the human female has not kept pace with the increase in life expectancy human beings have experienced recently. [ 23 ]  Utian is known as the world's most prolific author of studies in the field of menopause, [ 24 ]  including 26 authored or co-authored articles during the first ten years of the field's existence and more than 200 over his career. [ 25 ]


Vaginal estrogen  is a form of  estrogen  that is delivered by  intravaginal administration . Vaginally administered estrogens are thereby exerting their effects mainly in the nearby tissue, with more limited  systemic effects  compared to  orally administered  estrogens. [ 1 ]  It will not protect against osteoporosis. [ 2 ]  With perhaps the exception of the  Femring , [ 3 ]  it also will not alleviate the  hot flashes  and hormonal imbalance caused by menopause. [ 2 ]


Vaginally administered estrogen are usually used to treat some menopausal symptoms that are isolated to the  vagina ,  vulva  and  urethra . [ 4 ]


Most of the vaginally administered estrogens are synthetic and therefore cause the following side effects [ 9 ]


Serious side effects:


Less serious side effects may include: [ 10 ]


Estrogen administered vaginally should not be given to persons who are:


Estrogen should not be used while pregnant as it could cause serious  birth defects .


Estrogen passes into the breast milk and will cause a decrease in the production and quality of  breast milk .


To effectively alleviate the symptoms of menopause, it is best to take oral estrogen instead of topical estrogen since the results are systemic and it will rejuvenate the entire reproductive system and not just the  perineal area . [ 11 ] [ additional citation(s) needed ]


Phytoestrogens  are plant derived compounds found in a wide variety of foods. Several health benefits including a lowered risk of osteoporosis, heart disease, breast cancer, and menopausal symptoms are frequently attributed to phytoestrogens but many are also considered to have the potential to cause adverse health effects. [ 12 ]  Plants such as  Kacip Fatimah  have been found to contain phytoestrogens that could alleviate some symptoms of menopause. [ 13 ]


The  Wiley Protocol  is a form of  bioidentical hormone replacement therapy  (BHRT) devised and advocated by author  T. S. Wiley .  The protocol claims to relieve the  symptoms of menopause  but is also promoted as increasing overall health through the recreation of a pre-menopausal woman's monthly hormonal cycle using rhythmic doses of hormones standardized to a uniform purity.  Wiley claims the protocol is a step beyond the  symptomatic treatment  of conventional  hormone replacement therapy .


The protocol has been criticized by members of the medical community for the dosages of the hormones used, side effects of the treatment, potential physiologic effects, Wiley's lack of medical or  clinical  qualifications to design the protocol, lack of  empirical evidence  demonstrating it as safe or effective, ethical problems with the  clinical trial  that is being run to test it and potential financial conflicts of interest regarding financial incentives.


The Wiley Protocol uses  bioidentical  hormones, specifically  estradiol  and  progesterone .  Hormones are applied  transdermally , using an oil-based skin cream for  topical  administration. [ 1 ] [ self-published source? ]   Doses of the hormones vary throughout a 28-day cycle that is designed to mimic the hormone levels and changes of a young woman who experiences regular  menstruation , with each hormone cycling and peaking at separate times throughout the period. [ 2 ]   The protocol is promoted as differing from conventional hormone replacement therapy in several ways:


The protocol also includes a follow-up program to monitor the  serum  of the bioidentical hormones. [ 1 ] [ self-published source? ]


Wiley has stated that in her opinion, the most important aspect of the protocol is the specific schedule and levels of the hormone doses rather than their bioidentical nature. [ 3 ]


A  patent  was granted for the protocol in 2011 for the specific blend of hormones and dosing method. [ 4 ]


Concerns have been raised that  serum levels  may not be an acceptable marker for  transdermally administered  hormones, that some women have experienced significant side effects while following the protocol and have stopped using it, and that the dosages used are too high and not physiologic. [ 5 ] [ 6 ]


T. S. Wiley  and  Suzanne Somers  have been criticized by some physicians for their advocacy of the Wiley Protocol. A group of seven doctors issued a public letter to Somers and her publisher,  Crown , in which they state that the protocol is "scientifically unproven and dangerous" and cite Wiley's lack of medical and clinical qualifications. [ 7 ] [ 8 ]   The Wiley Protocol has been criticized as unethical due to the start of a Phase II  clinical trial  with no Phase I, a lack of approval by an  institutional review board , a lack of an experienced scientific investigator leading the trial, no  inclusion  or  exclusion criteria  and no evidence that the study population has been told that the research has not passed an ethical review, [ 6 ] [ 9 ]  as well as concerns over conflicts of interest regarding financial incentives. [ 6 ]


The  human reproductive system  includes the  male reproductive system , which functions to produce and deposit  sperm , and the  female reproductive system , which functions to produce  egg cells  and to protect and nourish the  fetus  until  birth . Humans have a high level of  sexual differentiation . In addition to differences in nearly every reproductive organ, there are numerous differences in typical  secondary sex characteristics .


Human reproduction  usually involves  internal fertilization  by  sexual intercourse . In this process, the  male  inserts his  penis  into the  female 's  vagina  and  ejaculates   semen , which contains  sperm . A small proportion of the sperm pass through the cervix into the uterus and then into the  fallopian tubes  for fertilization of the  ovum . Only one sperm is required to fertilize the ovum. Upon successful  fertilization , the fertilized ovum, or  zygote , travels out of the fallopian tube and into the  uterus , where it implants in the uterine wall. This marks the beginning of gestation, better known as  pregnancy , which continues for around nine months as the fetus develops. When the fetus has developed to a certain point, pregnancy is concluded with  childbirth , involving labor. During labor, the uterine muscles contract, and the  cervix dilates  typically over a period of hours, allowing the infant to pass from the uterus through the vagina. [ 1 ]  Human infants are entirely dependent on their caregivers and require  parental care . Infants rely on their caregivers for comfort, cleanliness, and food. Food may be provided by  breastfeeding  or  formula feeding . [ 2 ]


The human female reproductive system is a series of organs primarily located inside the body and around the  pelvic  region of a  female  that contribute towards the  reproductive  process. The human female reproductive system contains three main parts: the vagina, which leads from the  vulva , the vaginal opening, to the uterus; the  uterus , which holds the developing fetus; and the  ovaries , which produce the female's ova. The  breasts  are involved during the parenting stage of reproduction, but in most classifications they are not considered to be part of the female reproductive system. [ 3 ]


The vagina meets the outside at the  vulva , which is made up of the  labia ,  clitoris  and  vestibule ; [ 4 ]  during intercourse this area is lubricated by mucus secreted by the  Bartholin's glands . The  vagina  is attached to the uterus through the  cervix , while the uterus is attached to the ovaries via the  fallopian tubes . Each ovary contains hundreds of egg cells or ova (singular  ovum ).


Approximately  every 28 days , the  pituitary gland  releases a  hormone  that stimulates some of the ova to develop and grow. One ovum is released and it passes through the fallopian tube into the uterus. Hormones produced by the ovaries prepare the uterus to receive the ovum. The lining of the uterus, called the  endometrium , and unfertilized ova are shed each cycle through the process of  menstruation . If the ova is fertilized by sperm, it attaches to the endometrium and the fetus develops. [ 3 ]


The male reproductive system is a series of organs located outside the body and around the  pelvis  region of a  male  that contribute towards the reproduction process. The primary direct function of the male reproductive system is to provide the male  sperm  for fertilization of the ovum. [ 3 ]


The major reproductive organs of the male can be grouped into three categories. The first category produces and stores sperm ( spermatozoa ). These are produced in the  testicles , which are housed in the temperature-regulating  scrotum ; immature sperm then travel to the  epididymides  for development and storage. The second category are the ejaculatory fluid producing glands which include the  Cowper's gland  (also called bulbourethral gland),  seminal vesicles ,  prostate , and  vas deferens . The final category are those used for  copulation  and deposition of the sperm within the female; these include the  penis ,  urethra , and  vas deferens . [ 3 ]


Major secondary sexual characteristics include a larger, more muscular stature, deepened voice,  facial  and  body hair , broad shoulders, and the development of an  Adam's apple . [ 5 ]  An important sexual hormone of males is  androgen , particularly  testosterone . [ 6 ]


The testes release a hormone that controls the development of sperm. This hormone is also responsible for the development of physical characteristics in men, such as facial hair and a deep voice.


The  development of the reproductive system  and the  development of the urinary system  are closely tied to the  development  of the human fetus. Despite the differences between them, the  adult   male  and  female  are  determined  in early development in the 6th week. The gonads and external genitals are derived from the  intermediate mesoderm . [ 7 ]  The three main fetal precursors of the reproductive organs are the  Wolffian duct , the  Müllerian ducts , and the  gonads .  Endocrine  hormones are a well-known and critical controlling factor in the normal differentiation of the reproductive system. [ 8 ]


The Wolffian duct forms the  epididymis ,  vas deferens ,  ejaculatory duct , and  seminal vesicle  in the male reproductive system, but essentially disappears in the female reproductive system. [ 9 ]  The reverse is true for the Müllerian duct, as it essentially disappears in the male reproductive system and forms the fallopian tubes, uterus, and vagina in the female system. In both sexes, the gonads go on to form the testes and ovaries; because they are derived from the same undeveloped structure, they are considered  homologous  organs. There are a number of other homologous structures shared between male and female reproductive systems. However, despite the similarity in function of the female fallopian tubes and the male epididymis and vas deferens, they are not homologous but rather  analogous  structures as they arise from different fetal structures.


Gametes are produced within the gonads through a process known as  gametogenesis . This occurs when certain types of  germ cells  undergo  meiosis  to split the normal  diploid  number of  chromosomes  (n=46) into  haploid  cells containing only 23 chromosomes. [ 10 ]


In males, this process is known as  spermatogenesis  and occurs only after  puberty  in the  seminiferous tubules  of the testes. The immature  spermatozoa  or sperm are then sent to the  epididymis , where they gain a tail, enabling  motility . Each of the original diploid germ cells or primary  spermatocytes  forms four functional gametes, each forever young. [ clarification needed ]  The production and survival of sperms require a temperature below the normal core body temperature. Since the scrotum, where the testes is present, is situated outside the body cavity, it provides a temperature about 3 °C below normal body temperature.


In females, gametogenesis is known as  oogenesis ; this occurs in the  ovarian follicles  of the ovaries. This process does not produce mature ovum until puberty. In contrast with males, each of the original diploid germ cells or primary  oocytes  will form only one mature ovum, and three  polar bodies  which are not capable of fertilization. It has long been understood that in females, unlike males, all the primary oocytes ever found in a female will be created prior to birth, and that the final stages of ova production will then not resume until puberty. [ 10 ]  However, recent scientific research has challenged that hypothesis. [ 11 ]  This new research indicates that in at least some species of mammal, oocytes continue to be replenished in females well after birth. [ 12 ]


In male  germ cells  and  spermatozoa , and also in female  oocytes , special  DNA repair  mechanism are present that function to maintain the integrity of the  genomes  that are to be passed on to progeny. [ 13 ]   These DNA repair pathways include  homologous recombinational  repair,  non-homologous end joining ,  base excision repair  and  DNA mismatch repair . [ 13 ]


Like all complex organ systems, the human reproductive system is affected by many diseases. There are four main categories of reproductive diseases in humans. They are:


Specific reproductive diseases are often  symptoms  of other diseases and  disorders , or have multiple, or unknown causes making them difficult to classify. Examples of unclassifiable disorders are  Peyronie's disease  in males and  endometriosis  in females. Many congenital conditions cause reproductive abnormalities, but are better known for their other symptoms. These include:  Turner syndrome ,  Klinefelter's syndrome ,  cystic fibrosis , and  Bloom syndrome . [ 15 ]


A  gonad ,  sex gland , or  reproductive gland [ 1 ]  is a  mixed gland  and  sex organ  that produces the  gametes  and  sex hormones  of an organism.  Female  reproductive cells are  egg cells , and  male  reproductive cells are  sperm . [ 2 ]  The male gonad, the  testicle , produces sperm in the form of  spermatozoa . The female gonad, the  ovary , produces egg cells. Both of these gametes are  haploid  cells. Some  hermaphroditic  animals (and some humans  — see  Ovotesticular syndrome ) have a type of gonad called an  ovotestis .


It is hard to find a common origin for gonads, but gonads most likely  evolved independently  several times. [ 3 ]


The gonads are controlled by  luteinizing hormone  (LH) and  follicle-stimulating hormone  (FSH), produced and secreted by  gonadotropes or gonadotrophins  in the  anterior pituitary gland . [ 4 ]  This secretion is regulated by  gonadotropin-releasing hormone  (GnRH) produced in the  hypothalamus . [ 5 ] [ 6 ]


The gonads develop from three sources; the mesothelium, underlying mesenchyme and the primordial germ cells. Gonads start developing as a common primordium (an organ in the earliest stage of development), in the form of  genital ridges , [ 7 ]  at the sixth week, which are only later  differentiated  to male or female  sex organs  (except when they are not differentiated). The presence of the  SRY   gene , [ 8 ]  located on the short arm of the  Y chromosome  and encoding the  testis determining factor , usually determines male sexual differentiation. In the absence of the SRY gene from the Y chromosome, usually the female sex (ovaries instead of testes) will develop. The  development of the gonads  is a part of the  development of the urinary and reproductive organs .


The gonads are subject to many diseases, such as  hypergonadism ,  hypogonadism ,  agonadism , tumors, and cancer, among others. [ citation needed ]


A delay in having children is common in the developed world and this delay is often associated with ovarian  female infertility  and subfertility. Ovarian aging is characterized by progressive decline of the quality and number of  oocytes . [ 9 ]  This decline is likely due, in part, to reduced expression of genes that encode proteins necessary for  DNA repair  and  meiosis . [ 10 ] [ 11 ]  Such reduced expression can lead to increased  DNA damage  and errors in meiotic  recombination . [ 9 ]


The testes of older men often have  sperm  abnormalities that can ultimately lead to  male infertility . [ 12 ]   These abnormalities include accumulation of DNA damage and decreased DNA repair ability. [ 12 ]   During spermatogenesis in the testis, spontaneous new mutations arise and tend to accumulate with age. [ 13 ]


This  list of related male and female reproductive organs  shows how the  male  and  female  reproductive organs and the  development of the reproductive system  are related, sharing a common developmental path. This makes them biological  homologues . These organs differentiate into the respective sex organs in males and females.


The external genitalia of both  males  and  females  have similar origins. They arise from the  genital tubercle  that forms anterior to the cloacal folds (proliferating mesenchymal cells around the cloacal membrane). The caudal aspect of the cloacal folds further subdivides into the posterior anal folds and the anterior urethral folds. Bilateral to the urethral fold, genital swellings become prominent. These structures are the future  scrotum  and  labia majora  in males and females, respectively.


The genital tubercles of an eight-week-old embryo of either sex are identical. They both have a  glans  area, which will go on to form the  clitoral glans  (females) or  penile glans  (males), a urogenital fold and groove, and an anal tubercle. At around ten weeks, the external genitalia are still similar. At the base of the glans, there is a groove known as the coronal sulcus or corona glandis. It is the site of attachment of the future prepuce. Just anterior to the anal tubercle, the caudal end of the left and right urethral folds fuse to form the urethral raphe. The lateral part of the genital tubercle (called the lateral tubercle) grows longitudinally and is about the same length in either sex.


The male external genitalia include the  penis  and the  scrotum . The female external genitalia include the  clitoris , the  labia , and the  vestibule , which are collectively called the  vulva . External genitalia vary widely in external appearance among different people.


One difference between the glans penis and the glans clitoridis is that the glans clitoridis packs nerve endings into a volume only about one-tenth the size of the glans penis. Therefore, the glans clitoridis has greater variability in cutaneous corpuscular receptor density (1-14 per 100× high-powered field) compared with the glans penis (1-3 per 100× high-power field). Touch for touch, this concentration of nerves makes the glans clitoridis more sensitive than the glans penis. As a result, many women can feel discomfort or pain with anything more than a gentle touch. [ 3 ]


This a list of  species ,  genera , and other biological  taxa  named after  human genitals .


The  urethra  ( pl. :  urethras  or  urethrae ) is the tube that connects the  urinary bladder  to the  urinary meatus , [ 1 ] [ 2 ]  through which  placental mammals   urinate  and  ejaculate . [ 3 ]  In non-mammalian  vertebrates , the urethra also transports semen but is separate from the urinary tract. [ 4 ]


The external  urethral sphincter  is a  striated muscle  that allows voluntary control over urination. [ 5 ]  The  internal sphincter , formed by the involuntary  smooth muscles  lining the bladder neck and urethra, receives its nerve supply by the  sympathetic  division of the  autonomic nervous system . [ 6 ]  The internal sphincter is present both in males and females. [ 7 ] [ 8 ] [ 9 ]


The urethra is a fibrous and muscular tube which connects the  urinary bladder  to the  external urethral meatus . Its length differs between the sexes, because it passes through the  penis  in males.


In the human male, the urethra is on average 18 to 20 centimeters (7 to 8 inches) long and opens at the end of the external urethral meatus. [ 10 ]


The urethra is divided into four parts in men, named after the location: [ 10 ]


These openings are collectively called the verumontanum (colliculus seminalis).
The prostatic urethra is a common site of obstruction to outflow of urine in BPH patients


Stratified squamous  – distally


There is inadequate data for the typical length of the male urethra; however, a study of 109 men showed an average length of 22.3 cm (SD = 2.4 cm), ranging from 15 cm to 29 cm. [ 14 ]


The urethra in male placental mammals is typically longer than in females. [ 15 ]


In the human female, the urethra is about 4 cm long, [ 10 ] [ 12 ]  having 6 mm diameter, [ 12 ]  and exits the body between the  clitoris  and the  vaginal opening , extending from the  internal  to the  external urethral orifice . The meatus is located below the clitoris. It is placed behind the  symphysis pubis , embedded in the anterior wall of the vagina, and its direction is obliquely downward and forward; it is slightly curved with the concavity directed forward. The proximal two-thirds of the urethra is lined by  transitional epithelial cells , while the distal third is lined by  stratified squamous epithelial cells . [ 16 ]


Between the  superior  and  inferior fascia  of the  urogenital diaphragm , the female urethra is surrounded by the  urethral sphincter .


The urethra in female placental mammals is typically shorter than in the male. [ 15 ]


The cells lining the urethra (the  epithelium ) start off as  transitional cells  as it exits the bladder, which are variable layers of flat to cuboidal cells that change shape depending on whether they are compressed by the contents of the urethra. [ 17 ]  Further along the urethra there are  pseudostratified columnar  and  stratified columnar  epithelia. [ 17 ]  The lining becomes  multiple layers of flat cells  near the end of the urethra, which is the same as the external skin around it. [ 17 ]


There are small  mucus -secreting urethral glands, as well as bulbo-urethral glands of Cowper, that secrete mucous acting to lubricate the urethra. [ 17 ]


The urethra consists of three coats: muscular, erectile, and mucous, the muscular layer being a continuation of that of the bladder.


Somatic  (conscious) innervation of the  external urethral sphincter  is supplied by the  pudendal nerve .


In the developing  embryo , at the hind end lies a  cloaca . This, over the fourth to the seventh week, divides into a  urogenital sinus  and the beginnings of the  anal canal , with a wall forming between these two inpouchings called the  urorectal septum . [ 18 ]  The urogenital sinus divides into three parts, with the middle part forming the urethra; the upper part is largest and becomes the  urinary bladder , and the lower part then changes depending on the biological sex of the embryo. [ 18 ]  The cells lining the urethra (the epithelium) come from  endoderm , whereas the connective tissue and smooth  muscle  parts are derived from  mesoderm . [ 18 ]


After the third month, urethra also contributes to the development of associated structures depending on the biological sex of the embryo. In the male, the epithelium multiples to form the  prostate . In the female, the upper part of the urethra forms the urethra and  paraurethral glands . [ 18 ]


The urethra is the vessel through which urine passes after leaving the bladder. During urination, the smooth muscle lining the urethra relaxes in concert with bladder contraction(s) to forcefully expel the urine in a pressurized stream. Following this, the urethra re-establishes muscle tone by contracting the smooth muscle layer, and the bladder returns to a relaxed, quiescent state. Urethral smooth muscle cells are mechanically coupled to each other to coordinate mechanical force and electrical signaling in an organized, unitary fashion. [ 19 ]


The male urethra is the conduit for  semen  during  orgasm . [ 3 ]  Urine is removed before ejaculation by  pre-ejaculate  fluid – called Cowper's fluid – from the bulbourethral gland. [ 20 ] [ 21 ]


Infection of the urethra is  urethritis , which often causes purulent urethral discharge. [ 22 ]  It is most often due to a  sexually transmitted infection  such as  gonorrhoea  or  chlamydia , and less commonly due to other bacteria such as  ureaplasma  or  mycoplasma ;  trichomonas vaginalis ; or the viruses  herpes simplex virus  and  adenovirus . [ 22 ]  Investigations such as a  gram stain  of the discharge might reveal the cause;  nucleic acid testing  based on the  first urine sample passed in a day , or a swab of the urethra sent for  bacterial culture and sensitivity  may also be used. [ 22 ]  Treatment usually involves  antibiotics  that treat both gonorrhoea and chlamydia, as these often occur together. [ 22 ]  A person being treated for urethritis should not have sex until the infection is treated, so that they do not spread the infection to others. [ 22 ]  Because of this spread, which may occur during an  incubation period  before a person gets symptoms, there is often  contact tracing  so that sexual partners of an affected person can be found and treatment offered. [ 22 ]


Cancer can also develop in the lining of the urethra. [ 23 ]  When cancer is present, the most common symptom in an affected person is  blood in the urine ; a physical  medical examination  may be otherwise normal, except in late disease. [ 23 ]   Cancer of the urethra  is most often due to cancer of the cells lining the urethra, called  transitional cell carcinoma , although it can more rarely occur as a  squamous cell carcinoma  if the type of cells lining the urethra have changed, such as due to a chronic  schistosomiasis  infection. [ 23 ]  Investigations performed usually include collecting a sample of urine for an inspection for malignant cells under a microscope, called  cytology , as well as examination with a flexible camera through the urethra, called  urethroscopy . If a malignancy is found, a  biopsy  will be taken, and a  CT scan  will be performed of other body parts (a  CT scan of the chest, abdomen and pelvis ) to look for additional  metastatic  lesions. [ 23 ]  After the cancer is  staged , treatment may involve  chemotherapy . [ citation needed ]


Passage of  kidney stones  through the urethra can be painful. Damage to the urethra, such as by kidney stones, chronic infection, cancer, or from catheterisation, can lead to narrowing, called a  urethral stricture . [ 24 ]  The location and structure of the narrowing can be investigated with a  medical imaging  scan in which dye is injected through the urinary meatus into the urethra, called a  retrograde urethrogram . [ 25 ]  Additional forms of imaging, such as  ultrasound ,  computed tomography  and  magnetic resonance imaging  may also be used to provide further details. [ 25 ]


Injuries to the urethra (e.g., from a  pelvic fracture [ 26 ] )


Foreign bodies in the urethra  are uncommon, but there have been medical case reports of self-inflicted injuries, a result of insertion of foreign bodies into the urethra such as an electrical wire. [ 27 ]


Hypospadias  and  epispadias  are forms of abnormal development of the urethra in the male, where the  meatus  is not located at the  distal  end of the penis (it occurs lower than normal with hypospadias, and higher with epispadias). In a severe  chordee , the urethra can develop between the penis and the scrotum.


A tube called a  catheter  can be inserted through the urethra to drain urine from the bladder, called an  indwelling urinary catheter ; or, to bypass the urethra, a catheter may be directly inserted through the abdominal wall into the bladder, called a  suprapubic catheter . [ 28 ]  This may be to relieve or bypass an obstruction, to monitor  how much urine someone produces , or because a person has difficulty urinating, for example due to a  neurological  cause such as  multiple sclerosis . [ 28 ]  Complications that are associated with catheter insertion can include  catheter-associated infections , injury to the urethra or nearby structures, or pain. [ 28 ]


In all  mammals , with the exception of  monotremes , and in both sexes, the urethra serves primarily to drain and excrete urine, which in mammals, collects in the urinary bladder and is released from there into the urethra. In addition, the closing mechanisms of the urethra, together with  immunoglobulins , largely prevent germs from penetrating the inside of the body. [ 29 ]  In  marsupials , the female's urethra empties into the  urogenital sinus . [ 30 ]


The word "urethra" comes from the  Ancient Greek  οὐρήθρα –  ourḗthrā . The stem "uro" relating to urination, with the structure described as early as the time of  Hippocrates . [ 31 ]  Confusingly however, at the time it was called "ureter". Thereafter, terms "ureter" and "urethra" were variably used to refer to each other thereafter for more than a millennia. [ 31 ]  It was only in the 1550s that anatomists such as  Bartolomeo Eustacchio  and  Jacques Dubois  began to use the terms to specifically and consistently refer to what is in modern English called the ureter and the urethra. [ 31 ]  Following this, in the 19th and 20th centuries, multiple terms relating to the structures such as  urethritis  and  urethrography , were coined. [ 31 ]


Kidney stones have been identified and recorded about as long as written historical records exist. [ 32 ]  The urinary tract as well as its function to drain urine from the kidneys, has been described by  Galen  in the second century AD. [ 33 ]  Surgery to the urethra to remove kidney stones has been described since at least the first century AD by  Aulus Cornelius Celsus . [ 33 ]


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The  acrosome  is an  organelle  that develops over the  anterior  (front) half of the head in the  spermatozoa  (sperm cells) of humans and many other animals. It is a cap-like structure derived from the  Golgi apparatus . In  placental mammals , the acrosome contains degradative  enzymes  (including  hyaluronidase  and  acrosin ). [ 1 ]  These enzymes break down the outer membrane of the  ovum , [ 2 ]  called the  zona pellucida , allowing the  haploid   nucleus  in the sperm cell to join with the haploid nucleus in the ovum.
This shedding of the acrosome, known as the  acrosome reaction , can be stimulated  in vitro  by substances that a sperm cell may encounter naturally, such as  progesterone [ 3 ]  or  follicular fluid , as well as the more commonly used calcium  ionophore  A23187. [ 4 ]   This can be done to serve as a positive control when assessing the acrosome reaction of a sperm sample by  flow cytometry [ 5 ]  or  fluorescence microscopy . This is usually done after staining with a fluoresceinated  lectin  such as FITC-PNA, FITC-PSA, FITC-ConA, or fluoresceinated antibody such as FITC-CD46. [ 6 ]


In the case of  globozoospermia  (sperm with round heads), the  Golgi apparatus  is not transformed into the  acrosome , causing  male infertility . [ 7 ]


The  ampulla pulla of vas deferens , also called the  ampulla pulla of ductus deferens , is an enlargement  of the  vas deferens  at the  pulla fundus of the   bladder  which acts as a reservoir for sperm. This structure is seen in some  mammalian  and  squamate  species and is sometimes tortuous in shape.


The  appendix testis  (or  hydatid of Morgagni ) is a  vestigial  remnant of the  Müllerian duct , present on the upper pole of the  testis  and attached to the  tunica vaginalis . It is present about 90% of the time. [ citation needed ]


The appendix of testis can occasionally become twisted, causing acute one-sided testicular pain and may require surgical excision to achieve relief. One third of patients present with a palpable "blue dot" discoloration on the scrotum.  This is nearly diagnostic of this condition. If clinical suspicion is high for the serious  differential diagnosis  of testicular torsion, a surgical exploration of the scrotum is warranted. Torsion of the appendix of testis occurs at ages 0–15 years, with a mean at 10 years, which is similar to that of testicular torsion. [ 1 ]


The  appendix of the epididymis  (or  pedunculated hydatid ) is a small stalked appendage (sometimes duplicated) on the head of the  epididymis . It is usually regarded as a detached  efferent duct .


This structure is derived from the  Wolffian duct  (mesonephric duct) as opposed to the  appendix testis  which is derived from the  Müllerian duct  (paramesonephric duct) remnant.


This article incorporates text in the  public domain  from  page 1242  of the 20th edition of   Gray's Anatomy   (1918)


Blennorrhea  is  mucous  discharge, especially from the  urethra  or  vagina  (that is, mucus  vaginal discharge ). [ 1 ] Blennorrhagia  is an excess of such discharge, [ 2 ]  often specifically referring to that seen in  gonorrhea .


The  body  or  shaft of the penis  is the free portion of the  human penis  that is located outside of the  pelvic cavity . [ 1 ]  It is the continuation of the internal  root , which is embedded in the  pelvis  and extends to the  glans . [ 2 ]  It is made up of the two  corpora cavernosa  and the  corpus spongiosum  on the underside. The corpora cavernosa are intimately bound to one another with a dorsally fenestrated  septum , which becomes a complete one before the  penile crura . [ 3 ]  The body of the penis is  homologous  to the female  clitoral body . [ 4 ] [ 5 ] [ 6 ]


The body of the penis is suspended from the  pubic symphysis . [ 7 ]  It has two surfaces; the  dorsal  and the  ventral  or  urethral . The  penile raphe  runs on its ventral surface.


The body is surrounded by a bi-layered model of  tunica albuginea  in which a distal ligament buttresses the glans penis and plays an integral role to the penile fibroskeleton, and the structure is called "os analog", a term coined by  Geng Long Hsu  in the Encyclopedia of Reproduction. [ 3 ]  This indispensable structure is a continuation of the body of the human penis, differing from other mammalian penises, in that it has no  baculum  (or erectile bone) and instead relies exclusively on engorgement with blood to reach its  erect state . It is a remnant of the baculum that evolved likely due to change in mating practice. [ 8 ]


A shallow groove, which marks their junction on the upper surface lodges the  deep dorsal vein of the penis , which is flanked by a pair of cavernosal veins of the penis, [ 3 ]  while a deeper and wider groove between them on the surface below contains the corpus spongiosum. The body is ensheathed by  fascia , which includes tunica albuginea,  Buck's fascia ,  dermis , and skin.


This article incorporates text in the  public domain  from  page 1249  of the 20th edition of   Gray's Anatomy   (1918)


The  Bowman–Heidenhain hypothesis  is an early explanation of  renal function  and  urinary   secretion .


The hypothesis states that the  kidney  is first and foremost a secreting  gland . According to the theory,  glomeruli  are merely filters, while the  tubules  are the true secretory structures. [ 1 ]  To prove his  hypothesis , Rudolph Heidenhain injected  methylene blue  into an animal's  bloodstream , which soon appeared in the  urine . More evident proof of this theory is that when the tubules are destroyed, urine becomes watery and  urea  and other toxic products remain in the  blood . [ 2 ]


This theory was later merged with the  Ludwig theory  to form the modern theory. [ 3 ]


The  bulb of penis  is the proximal/posterior bulged [ 1 ]  end of the (unpaired median)  corpus spongiosum penis . Together with the two  crura  (one crus on each side of the bulb), it constitutes the  root of the penis . [ 2 ]  It is covered by the  bulbospongiosus .


Proximally/posteriorly, the bulb of penis extends towards the  perineal body . The bulb exhibits a slight yet palpable midline notch upon its inferior aspect. [ 2 ]


The male urethra enters the penis at the superior aspect of the anterior part of the bulb (most of the bulb is thus situated inferoposteriorly to the urethra), and the  arteries of bulb of penis  enter near the urethra. [ 2 ]


The bulb of penis is  homologous  to the  vestibular bulbs  in females. [ 3 ]


Cavernous tissue  refers to  blood -filled spaces lined by  endothelium  and surrounded by  smooth muscle . It is present in the  erectile tissue  of the  penis  and  clitoris . [ 1 ]


This  cardiovascular system  article is a  stub . You can help Wikipedia by  expanding it .


Cephalopelvic disproportion (CPD)  exists when the capacity of the  pelvis  is inadequate to allow the  fetus  to negotiate the  birth canal . This may be due to a small pelvis, a nongynecoid pelvic formation, a large fetus, an unfavorable orientation of the fetus, or a combination of these factors. Certain medical conditions may distort pelvic bones, such as  rickets  or a pelvic  fracture , and lead to CPD.


Transverse diagonal measurement has been proposed as a predictive method. [ 1 ]


1.	Prolonged Labor: Labor that doesn’t progress as expected, particularly during the active phase.


2.	Failure to Progress: Lack of dilation or descent of the baby despite strong contractions.


3.	Severe Pain: Intense pain that is disproportionate to normal labor pain.


4.	Fetal Distress: Signs like abnormal heart rate patterns detected via fetal monitoring.


5.	Maternal Exhaustion: Extreme fatigue in the mother due to prolonged labor.


6.	High Station: The baby’s head remains high in the pelvis and doesn’t descend despite strong contractions.


Diagnosis of CPD usually occurs during labor, often requiring medical interventions such as a cesarean section (C-section) to ensure the safety of both mother and baby.


A large fetus can be one cause of CPD. A large fetus can be caused by  gestational diabetes ,  postterm pregnancy , genetic factors, and  multiparity . [ citation needed ]


The shape of the pelvis can also be a cause of CPD. The pelvis may be too small, or the shape of the pelvis may be malformed. [ 2 ]  Shorter women are more likely to have CPD [ 1 ]  as are adolescents. [ 3 ]


Diagnosis of CPD may be made when there is  failure to progress , but not all cases of prolonged labour are the result of CPD. Use of ultrasound to measure the size of the fetus in the womb is controversial, as these methods are often inaccurate and may lead to unnecessary  caesarian section ; a trial of labour is often recommended even if size of the fetus is estimated to be large. [ 2 ]


Theoretically,  pelvimetry  may identify cephalo-pelvic disproportion. However, a woman's pelvis loosens up before birth (with the help of hormones). A  Cochrane review  in 2017 found that there was too little evidence to show whether pelvimetry is beneficial and safe when the baby is in  cephalic presentation . [ 4 ]  A review in 2003 came to the conclusion that pelvimetry does not change the management of pregnant women, and recommended that all women should be allowed a trial of labor regardless of pelvimetry results. [ 5 ]  It considered routine performance of pelvimetry to be a waste of time, a potential liability, and an unnecessary discomfort. [ 5 ]


In the case of a fetus being too large, some obstetricians recommend  induction of labour  for earlier delivery. Diagnosis of CPD in active labour will usually result in a  Caesarian section. [ citation needed ]


Chyloderma  is swelling of the  scrotum  resulting from chronic  lymphatic  obstruction. [ 1 ]  Obstruction may be caused by a  nematode  such as  Wuchereria bancrofti . This condition is also known as  lymphscrotum  or  elephantiasis scroti .


The  corona of glans penis  (or, directly from the  Latin , the  corona glandis penis [ 1 ] ) or  penis crown  refers to the rounded projecting border or flare that forms at the base of the  glans  in  human males . The corona overhangs a  mucosal  surface, known as the neck of the  penis , which separates the shaft and the glans. [ 2 ]  The deep retro-glandular coronal  sulcus  forms between the corona and the neck of the penis. The two sides of the corona merge on the ventral midline forming the  septum glandis . [ 3 ]  The circumference of the corona is richly  innervated  and is described as a highly erogenous area of the glans. [ 4 ]


During the  embryonic  development of the male fetus, a thickening on the  epidermis  appears around the base of the developing glans. [ 5 ]  The thickening separates from the glans creating the preputial fold and the preputial lamina on its ventral surface. [ 6 ]  The lamina expands outwards over the  epithelium  of the glans and also backwards forming an ingrowing fold at the base of the glans that will become the coronal sulcus. [ 7 ]


The corona and the neck are highly  vascularized  areas of the penis. The axial and  dorsal penile arteries  merge together at the neck before entering the glans. [ 8 ]  Branches of the dorsal artery of the penis curve around the distal shaft to enter the  frenulum  and the glans from its ventral surface. [ 9 ]  Small venous tributaries deriving from the corona drain the glans forming a venous retro-coronal  plexus  before merging with the  dorsal veins . [ 8 ]


The circumference and the underside of the corona are densely innervated by several types of  nerve  terminals, including  genital corpuscles  and  free nerve endings , and are considered by males a highly  erogenous zone  of their penis. [ 4 ] [ 10 ]  The area is reported to be particularly responsive to  stimulation  and a source of distinct sexual pleasure. [ 11 ] [ 12 ]


In some males, small skin-colored bumps, known as  pearly penile papules , may appear at the circumference of the corona. Their appearance may vary from being hardly noticeable in some men to more prominent and well-defined in others. The papules are painless, harmless and non-sexually transmitted. They usually appear in late puberty and are thought to disappear with age. [ 13 ]  Even though they do not require treatment, they can easily be removed, especially for aesthetic purposes. [ 14 ]


A  cortical lobule  (or  renal lobule ) is a part of a  renal lobe . It consists of the  nephrons  grouped around a single  medullary ray , and draining into a single  collecting duct . Its near identical parallel is the  rectal   lobe [ citation needed ] , which is present in the majority of mammals.


The  cremasteric fascia  is a  fascia  in the  scrotum . As the  cremaster  descends, it forms a series of loops which differ in thickness and length in different subjects. At the upper part of the cord the loops are short, but they become in succession longer and longer, the longest reaching down as low as the  testis , where a few are inserted into the  tunica vaginalis . These loops are united together by  areolar tissue , and form a thin covering over the cord and testis, the cremasteric fascia.


The cremasteric fascia lies between the more superficial  external spermatic fascia  and the deeper  internal spermatic fascia . [ 1 ]  It is a continuation of the  aponeurosis  of the  abdominal internal oblique muscle . [ 2 ] [ 3 ]


This article incorporates text in the  public domain  from  page 414  of the 20th edition of   Gray's Anatomy   (1918)


This  muscle  article is a  stub . You can help Wikipedia by  expanding it .


Crossed dystopia  (also  unilateral fusion cross fused renal ectopia ) is a rare form of  renal ectopia  ( kidney  displacement) where both kidneys are on the same side of the  spine . [ 1 ]  In many cases, the two kidneys are fused together, yet retain their own  vessels  and  ureters . [ 2 ]  The ureter of the lower kidney crosses the midline to enter the  bladder  on the contralateral side. Both  renal pelves  can lie one above each other medial to the  renal parenchyma  (unilateral long kidney) or the pelvis of the crossed kidney faces laterally (unilateral S-shaped kidney).  Urogram  is diagnostic.


The anomaly can be diagnosed through ultrasound or  urography , but surgical intervention is only necessary if there are other complications, such as  tumors  or  pyelonephritis . [ citation needed ]


The  dorsal nerve of the clitoris  is a  nerve  in females that branches off the  pudendal nerve [ 1 ]  to innervate the  clitoris . The nerve is important for female sexual pleasure, [ 2 ]  and it may play a role in  clitoral erections . [ 3 ]


It travels from below the  inferior pubic ramus [ 4 ]  to the  suspensory ligament of the clitoris . At its thickest, the DNC is 2 mm (0.079 in) in diameter, visible to the naked eye during dissection. [ 2 ]  The DNC splits into two nerve branches on either side of the midline, closely following the crura of the clitoris. [ 3 ]


Some surgeries—for example, sling surgeries to treat female urinary incontinence—can damage the DNC, causing a loss of sensation in the clitoris. Understanding the nerve is important for urologists and gynecologists who may operate on organs near the DNC. [ 2 ] [ 4 ] [ 5 ]


The dorsal nerve of the clitoris is analogous to the  dorsal nerve of the penis  in males. [ 6 ]   It is a terminal branch of the  pudendal nerve . [ 1 ]


This  neuroanatomy  article is a  stub . You can help Wikipedia by  expanding it .


The  epoöphoron  lies in the  mesosalpinx  between the  ovary  and the  uterine tube , and consists of a few short tubules, the  ductuli transversi  which converge toward the ovary while their opposite ends open into a rudimentary duct, the ductus longitudinalis epoöphori ( duct of Gartner ).


The ductuli transversi of the epoophoron is a remnant of the tubules of the  Wolffian body  or mesonephros.


This article incorporates text in the  public domain  from  page 1255  of the 20th edition of   Gray's Anatomy   (1918)


Ectopic kidney  describes a  kidney  that is not located in its usual position ( ectopia ). This condition results from the kidney failing to ascend from its origin in the  true pelvis  or from a superiorly ascended kidney located in the  thorax . [ 1 ]


It has an incidence of approximately 1/900. [ 2 ]


Ejaculation disorders  are the most common sexual dysfunction in men. [ 1 ]  Common ejaculatory disorders include:  premature ejaculation ,  retrograde ejaculation ,  delayed ejaculation ,  anejaculation ,  inhibited ejaculation , and  anorgasmia . [ 2 ]


The  external spermatic fascia  ( intercrural  or  intercolumnar fascia ) is a thin membrane, prolonged downward around the surface of the  spermatic cord  and  testis . It is separated from the  dartos tunic  by  loose areolar tissue . It is occasionally referred to as 'Le Fascia de Webster' after an anatomist who once described it.


The external spermatic fascia is derived from the  aponeurosis  of the  abdominal external oblique muscle . [ 1 ] [ 2 ]  It is acquired by the  spermatic cord  at the  superficial inguinal ring . [ 1 ]


This article incorporates text in the  public domain  from  page 1238  of the 20th edition of   Gray's Anatomy   (1918)


The  external sphincter muscle of the female urethra  is a muscle which controls  urination  in females. The muscle fibers arise on either side from the margin of the inferior ramus of the pubis. They are directed across the pubic arch in front of the urethra, and pass around it to blend with the muscular fibers of the opposite side, between the urethra and vagina.


The term "urethrovaginal sphincter" ("sphincter urethrovaginalis") is sometimes used to describe the component adjacent to the  vagina . [ 1 ] [ 2 ] [ 3 ] [ 4 ] [ 5 ]


The "compressor urethrae" is also considered a distinct, adjacent muscle by some sources, [ 6 ] [ 7 ] [ 8 ] [ 9 ]


The muscle helps maintain  continence  of  urine  along with the  internal urethral sphincter  which is under control of the  autonomic nervous system . The external sphincter muscle prevents urine leakage as the muscle is tonically contracted via  somatic  fibers that originate in  Onuf's nucleus  and pass through  sacral spinal nerves  S2-S4 then the  pudendal nerve  to  synapse  on the muscle. [ 7 ] [ 10 ]


Voiding urine begins with voluntary relaxation of the external urethral sphincter. This is facilitated by inhibition of the somatic neurons in Onuf's nucleus via signals arising in the  pontine micturition center  and traveling through the  descending reticulospinal tracts .


This article incorporates text in the  public domain  from  page 431  of the 20th edition of   Gray's Anatomy   (1918)


The  external sphincter muscle of the male urethra , also  sphincter urethrae membranaceae ,  sphincter urethrae externus , surrounds the whole length of the  membranous urethra , and is enclosed in the  fascia  of the  urogenital diaphragm .


Its external fibers arise from the junction of the  inferior pubic ramus  and  ischium  to the extent of 1.25 to 2 cm., and from the neighboring fascia.


They arch across the front of the urethra and  bulbourethral  glands, pass around the urethra, and behind it unite with the muscle of the opposite side, by means of a tendinous  raphe .


Its innermost fibers form a continuous circular investment for the membranous urethra.


The muscle helps maintain  continence  of  urine  along with the  internal urethral sphincter  which is under control of the  autonomic nervous system . The external sphincter muscle prevents urine leakage as the muscle is tonically contracted via  somatic  fibers that originate in  Onuf's nucleus  and pass through  sacral spinal nerves  S2-S4 then the  pudendal nerve  to  synapse  on the muscle. [ 1 ] [ 2 ]


Voiding urine begins with voluntary relaxation of the external urethral sphincter. This is facilitated by inhibition of the somatic neurons in Onuf's nucleus via signals arising in the  pontine micturition center  and traveling through the  descending reticulospinal tracts . During ejaculation, the external sphincter opens and the internal sphincter closes. [ 3 ]


This article incorporates text in the  public domain  from  page 429  of the 20th edition of   Gray's Anatomy   (1918)


Facet cells  (also known as  umbrella cells , [ 1 ]  capping cells, superficial urotheliocytes) are a type of cells located in the  renal pelvis , the  ureters , and the  urethra . Umbrella cells form the outermost layer of the  urothelium , which is a special type of  epithelium  found in the  renal pelvis , the  ureters , and the  urethra . Umbrella cells are special in that they can contain  multiple nuclei . Their  apical membrane  contains numerous  invaginations , which allows the cells to stretch during  urination . Umbrella cells are linked together with tight  junctions  which:


Umbrella cells contain  uroplakin ia ,  uroplakin ib , uroplakin ii, and uroplakin iii. [ 3 ]  These increase the strength of the  urothelium . [ 3 ]


In renal physiology, the  filtration fraction  is the ratio of the  glomerular filtration rate  (GFR) over the  renal plasma flow  (RPF).


Filtration Fraction, FF = GFR/RPF, or

 F
 F
 =

 G
 F
 R

 R
 P
 F

 {\displaystyle FF={\frac {GFR}{RPF}}}

 .


The filtration fraction, therefore, represents the proportion of the fluid reaching the  kidneys  that passes into the  renal tubules .  It is normally about 20%.


GFR on its own is the most common and important measure of  renal function . However, in conditions such as  renal artery stenosis ,  blood flow  to the kidneys is reduced. Filtration fraction must therefore be increased in order to perform the normal functions of the kidney.  Loop diuretics  and  thiazide diuretics  decrease filtration fraction.


Catecholamines  ( norepinephrine  and  epinephrine ) increase filtration fraction by  vasoconstriction  of  afferent  and  efferent arterioles , possibly through activation of  alpha-1 adrenergic receptors .


Severe  hemorrhage  will also result in an increased filtration fraction.


The  follicular antrum  is the portion of an  ovarian follicle  filled with  follicular fluid . Appearance of the follicular antrum during follicular maturation is the first sign that a follicle has reached the next stage of maturation. It has changed from a primary follicle to a secondary follicle.


Follicular fluid  is a liquid which fills the  follicular antrum  and surrounds the  oocyte  in an  ovarian follicle .  This fluid is rich in  hyaluronic acid , and is used in a modified  intracytoplasmic sperm injection  (ICSI) called  physiological ICSI  (PICSI), semi-viscous and yellow in colour. [ 1 ]  Its components come mainly from  granulosa cells . [ 2 ]


The  fossa of vestibule of vagina  (or  fossa navicularis ) is a boat-shaped depression between the  vaginal opening / hymen  and the  frenulum labiorum pudendi  within the  vestibule . The small openings of the  Bartholin's ducts  can be seen in the grooves between the hymen and the  labia minora , on either side.


This article incorporates text in the  public domain  from  page 1323  of the 20th edition of   Gray's Anatomy   (1918)


The  frenulum of labia minora  ( fourchette  or  posterior commissure of the labia minora ) is a  frenulum  where the  labia minora  meet  posteriorly . [ 1 ]


The fourchette may be torn during  delivery  due to the sudden stretching of the  vulval  orifice, or during copulation.  To prevent this tearing in a haphazard manner,  obstetricians  and, less frequently,  midwives  may perform an  episiotomy , which is a deliberate cut made in the  perineum  starting from the fourchette and continuing back along the perineum toward the anus. Sometimes this surgical cut may extend to involve the perineal body and thus reduce anal sphincter function. Thus some obstetricians have opted to perform a posterior-lateral cut in the perineum to prevent this potential complication from occurring.


The fourchette may also be torn in acts of violence wherein forced entry occurs such as  rape . When the fourchette is torn, the bleeding which ensues sometimes requires surgical  suturing  for containment.


The fourchette is named with the  French  word for " fork " or " wishbone ", owing to its shape. (See  frenulum  for its etymology.)


The  fundiform ligament of the penis  is a structure of the external genitalia whose descriptions differ according to the source consulted. [ 1 ]


The 41st Edition of  Gray's Anatomy  (2015) and  Traité d'Anatomie humaine  do not acknowledge this structure. Some sources equate the fundiform ligament with the  Scarpa fascia . [ 1 ]


According to the  Medical Dictionary of the French Academy of Medicine  the fundiform ligament is a bilaterally paired bundle of fibres of the lateral lamina of the  suspensory ligament of penis  which curve around the lateral and inferior aspects of the penis to unite with the contralateral fundiform ligament beneath the urethral aspect of the penis; the two fundiform ligaments thus form a sling which offers structural support to the penis. [ 2 ]


Although rarely mentioned, this ligament is also found in females (at the  clitoris ). [ citation needed ]


A 2023 cadaveric study on 7 cadavers characterised the fundiform ligament as a structurally heterogenous structure that is superficial to the suspensory ligament of penis. The study identified three morphological types/variants of the fundiform ligament: a single triangular structure (attached proximally onto the linea alba); a doubled structure with accessory bundles (one medial main band and one lateral accessory band on each side); and an amourphous, ligamentous fibrous connective band structure. [ 1 ]


Gartner's duct , also known as  Gartner's canal  or the  ductus longitudinalis epoophori , is a potential  embryological  remnant in human female development of the  mesonephric duct  in the  development of the urinary and reproductive organs . [ 2 ]  It was discovered and described in 1822 by  Hermann Treschow Gartner .


Gartner's duct is located in the  uterus '  broad ligament . Its position is parallel with the lateral  uterine tube  and lateral walls of  vagina  and  cervix .


The paired mesonephric ducts in the  male , in contrast, go on to form the paired  epididymides ,  vasa deferentia ,  ejaculatory ducts  and  seminal vesicles .


In  females , they may persist between the layer of the  broad ligament of the uterus  and in the wall of the  vagina . [ citation needed ]


These may give rise to  Gartner's duct cysts . [ 3 ]


Genitourinary amoebiasis  or  renal amoebiasis  is a rare complication to  amoebic liver abscess , which in turn is a complication of  amoebiasis . It is believed to result from liver abscesses breaking open, whereupon the amoebas spread  through the blood  to the new locale. Genital involvement is thought to result from  fistula  formation from the liver or through  rectocolitis . The involvement causes lesions which exude a high degree of pus. [ 1 ]


The  germinal epithelium  is the  epithelial  layer of the  seminiferous tubules  of the  testicles . It is also known as the wall of the seminiferous tubules. The cells in the epithelium are connected via tight junctions.


There are two types of cells in the germinal epithelium. The large  Sertoli cells  (not dividing) function as supportive cells to the developing  sperm . The second cell type is the cells belonging to the  spermatogenic  cell lineage. These eventually develop into sperm cells ( spermatozoon ). Typically, the spermatogenic cells will make four to eight layers in the germinal epithelium. [ 1 ]


Gouverneur's syndrome  is characterised by  vesicointestinal fistula  with associated  suprapubic  pain, urinary frequency, pain on passing urine, and  tenesmus . [ 1 ] [ 2 ]  It is named after French physician R. Gouverneur. [ 3 ]


The  holonephros  is the  kidney  of the  larvae  of  cyclostomes  and the  Gymnophiona . The entire mass of nephrogenic tissue gives rise to this kidney, which is usually of simple form with a single  tubule  in each segment.


In  medicine ,  hyperspermia  is a condition in which a  male  has an abnormally large amount of  semen  or  ejaculate   volume [ 1 ]  and is generally defined when the ejaculate is above 6 mL. [ 2 ]  It is the opposite of  hypospermia , which is defined as a semen volume of less than 1.5 mL.


Hyperspermia alone does not appear to influence sperm health. However, large volumes of ejaculate may have lower concentrations of sperm, leading to low fertility. [ 3 ] [ 1 ]


In some cases, high semen volumes can be a symptom of  male accessory gland infection . [ 4 ]


The  internal spermatic fascia  ( infundibuliform fascia  or  Le deuxième fascia de Webster ) is a thin layer, which loosely invests the  spermatic cord .


The internal spermatic fascia is derived from the  transversalis fascia . [ 1 ] [ 2 ]  It is acquired by the  spermatic cord  at the  deep inguinal ring . [ 1 ]  It has very little  lymphatic drainage . [ 3 ]  It is mainly supplied by sensory afferents and the  sympathetic nervous system . [ 3 ]


This article incorporates text in the  public domain  from  page 1239  of the 20th edition of   Gray's Anatomy   (1918)


The  internal urethral orifice  is the opening of the  urinary bladder  into the  urethra . [ 1 ]


It is usually somewhat crescent-shaped. [ citation needed ]


It is formed by the  neck of the urinary bladder . It opens at the apex/inferior angle of the  trigone of the bladder , some 2-3 cm anteromedial to either  ureteral orifice . [ 1 ]


The  mucous membrane  immediately posterior to it presents a slight elevation in males - the  uvula vesicae  - caused by the middle lobe of the  prostate . [ citation needed ]


This article incorporates text in the  public domain  from  page 1232  of the 20th edition of   Gray's Anatomy   (1918)


Juxtaglomerular cells  ( JG cells ), also known as  juxtaglomerular granular cells  are  cells  in the  kidney  that synthesize, store, and secrete the enzyme  renin . [ 1 ]  They are specialized  smooth muscle cells  mainly in the walls of the  afferent arterioles  (and some in the  efferent arterioles ) [ citation needed ]  that deliver blood to the  glomerulus . In synthesizing renin, they play a critical role in the  renin–angiotensin system  and thus in  autoregulation  of the kidney.


Juxtaglomerular cells secrete renin in response to a drop in pressure detected by  stretch receptors  in the vascular walls, or when stimulated by  macula densa  cells. Macula densa cells are located in the distal convoluted tubule, and stimulate juxtaglomerular cells to release renin when they detect a drop in chloride concentration in  tubular fluid . Together, juxtaglomerular cells, extraglomerular mesangial cells and macula densa cells comprise the  juxtaglomerular apparatus .


In appropriately stained tissue sections, juxtaglomerular cells are distinguished by their granulated cytoplasm.


The juxtaglomerular cell is a cell that is located near the glomerulus, hence its name.


Similar to cardiac tissue, juxtaglomerular cells harbor  β1 adrenergic receptors . When stimulated by  epinephrine  or  norepinephrine , these receptors induce the secretion of renin. These cells also respond directly to a decrease in systemic blood pressure which is manifested as a lower renal perfusion pressure.


The  Kokko and Rector model  is a theory explaining the mechanism of generation of a gradient in the  inner medulla  of the  kidney . Unlike earlier theories explaining the mechanism using counter current mechanism (as is the case in the  outer medulla ), the driving force for salt reabsorption is stated to be urea accumulation. It has been proved that counter current mechanism cannot be the case in the  inner medulla , since there are no salt pumps, and the  cell membrane  is too  permeable  to salt. [ clarification needed ]


It has been proposed by Juha Kokko and Floyd Rector Jr. in 1972. [ 1 ]


Lacunae of Morgagni , also called the  urethral  lacunae of the male urethra ( lacunae urethralis ,  urethrae masculinae  or the  crypts of Morgagni ), are small depressions or recesses on the surface of the mucous membrane of the urethra. Their openings are usually directed  distally . The largest of these recesses is called  lacuna magna  (or the  sinus of Guérin , or  Guérin's sinus ), which is situated on the upper surface of the  fossa navicularis .


Located deeper within the lacunae are branching mucous  tubules  called the  glands of Littre . The lacunae of Morgagni are named after Italian  anatomist   Giovanni Battista Morgagni  (1682–1771).


The  medulla of ovary  (or  Zona vasculosa of Waldeyer ) is a highly vascular stroma in the center of the  ovary .  It forms from embryonic  mesenchyme  and contains blood vessels, lymphatic vessels, and nerves.


This stroma forms the tissue of the  hilum  by which the  ovarian ligament  is attached, and through which the blood vessels enter: it does not contain any  ovarian follicles .


This article incorporates text in the  public domain  from  page 1256  of the 20th edition of   Gray's Anatomy   (1918)


In anatomy, a  medullary ray   ( Ferrein's pyramid ) is the middle part of a  cortical lobule  (or renal lobule). Each consists of a group of  nephrons  in the  renal cortex . [ 1 ]  Their name is potentially misleading, as "medullary" refers to their destination, not their location. They travel perpendicular to the capsule, and extend from the cortex to the medulla. They may be visualised during  urography . [ 1 ]


Megaureter  is a medical anomaly whereby the  ureter  is abnormally  dilated .  Congenital  megaureter is an uncommon condition which is more common in males, may be bilateral, and is often associated with other congenital anomalies. The cause is thought to be  aperistalsis  of the distal ureter, leading to dilatation.  [ citation needed ]


The  cutoff  value for megaureter is when it is wider than 6 [ 1 ]  or 7 mm. [ 2 ]


A functional obstruction at the lower end of the ureter leads to progressive dilatation and a tendency to  infection . The ureteric orifice appears normal and a ureteric  catheter  passes easily. [ citation needed ]


Definitive  surgical treatment  involves refashioning the lower end of the affected ureter so that a tunnelled reimplantation into the  bladder  can be done to prevent reflux. [ citation needed ]


The larger  ovarian follicles  consist of an external fibrovascular coat, connected with the surrounding  stroma of the ovary  by a network of blood vessels, and an internal coat, which consists of several layers of nucleated cells, called the  membrana granulosa . It contains numerous  granulosa cells .


At one part of the mature follicle the cells of the membrana granulosa are collected into a mass which projects into the cavity of the follicle. This is termed the  discus proligerus .


The  mesometrium  is the  mesentery  of the  uterus . It constitutes the majority of the  broad ligament of the uterus , [ 1 ]  excluding only the portions adjacent to the  uterine tube  (the mesosalpinx) and  ovary  (the  mesovarium ).


It is adjacent to the  mesosalpinx .


The  ureter  is among the structures found in the mesometrium.


This  ligament -related article is a  stub . You can help Wikipedia by  expanding it .


The  mesosalpinx  is part of the lining of the  abdominal cavity  in  higher vertebrates , specifically the portion of the  broad ligament  that stretches from the  ovary  to the level of the  fallopian tube .


This article incorporates text in the  public domain  from  page 1261  of the 20th edition of   Gray's Anatomy   (1918)


The  mesovarium  is the portion of the  broad ligament  of the  uterus  that suspends the  ovaries . The ovary is not covered by the mesovarium; rather, it is covered by germinal epithelium.


At first, the  mesonephros  and  genital ridge  are suspended by a common  mesentery , but as the  embryo  grows the genital ridge gradually becomes pinched off from the mesonephros, with which it is at first continuous, though it still remains connected to the remnant of this body by a fold of  peritoneum . In the male, this is the  mesorchium , and in the female, this is the mesovarium.


Minimal mesangial glomerulonephritis  is a type of  glomerulonephritis  that is seen in 10% to 25% of  SLE  cases and is associated with mild clinical  symptoms .  Immune complexes  deposit in the  mesangium , with a slight increase in the  mesangial matrix  and  cellularity . [ 1 ]


Necrospermia  (or  necrozoospermia ) is a condition in which there is a low percentage of live and a very high percentage of immotile  spermatozoa  in  semen . [ 1 ]


Necrospermia is usually confused with asthenozoospermia, which is the inability of the sperm to move even when alive. To check for necrospermia, samples with a high percentage of immobile sperm are stained to check for vitality. If they are dead sperm they will be stained, as the membrane is broken and the dye enters indiscriminately. Necrozoospermia is a rare condition with a reported prevalence of 0.2–0.48% in infertile subjects. [ 2 ]


It has been claimed that necrospermia can be successfully treated in  Ayurveda . A single case report to that effect has been published. [ 3 ] [ dubious  –  discuss ]


Nephromegaly  is the process whereby a  kidney  or both kidneys become enlarged. [ 1 ]  Both  autosomal dominant  and  autosomal recessive polycystic kidney disease  can cause nephromegaly. [ citation needed ]


The  ovarian cortex  is the outer portion of the  ovary . The  ovarian follicles  are located within the ovarian cortex. The ovarian cortex is made up of  connective tissue .  [ 1 ]  Ovarian cortex  tissue transplant  has been performed to treat  infertility . [ 2 ] [ 3 ]


The  ovarian fossa  is a shallow depression on the lateral wall of the  pelvis , where in the  ovary  lies.


This ovarian fossa has the following boundaries:


This article incorporates text in the  public domain  from  page 1254  of the 20th edition of   Gray's Anatomy   (1918)


The  parametrium  is the fibrous and fatty  connective tissue  that surrounds the  uterus . [ 1 ]  This  tissue separates the supravaginal portion of the  cervix  from the  bladder . The parametrium lies in front of the cervix and extends laterally between the layers of the  broad ligaments . It connects the uterus to other tissues in the  pelvis . [ 1 ]   It is different from the  perimetrium , which is the outermost layer of the uterus.


The  uterine artery  and  ovarian ligament  are located in the parametrium.


An associated form of  pelvic inflammatory disease  is inflammation of the parametrium known as  parametritis .


The  paroophoron  (of Johnson;  pl. :  paroophora ) consists of a few scattered rudimentary tubules, best seen in a child, situated in the  broad ligament  between the  epoöphoron  and the  uterus . [ 1 ]  Named for the Welsh anatomist David Johnson who originally described the structure at the  University of Wales ,  Aberystwyth .


It is a remnant of the  mesonephric tubules [ 2 ]  and is   homologous  to the male  paradidymis .


A  pelvic kidney , also known as an  ectopic kidney , is a normal  kidney  located in the  pelvis , instead of the  abdomen . This occurs when a kidney does not ascend from its original location in the pelvis to its final location during  prenatal development . They usually present no  symptoms , but can increase risk of certain illnesses and healthcare problems.


Often, a person with a pelvic kidney will go through their whole life not even knowing they have a pelvic kidney.


While symptoms are uncommon, some people with a pelvic kidney may experience abdominal or back pain, fever,  hematuria , high blood pressure, or a burning sensation while urinating. [ 1 ]


Typically, the kidney functions normally despite being in the wrong location. [ 2 ]  However, it can develop complications. [ 3 ]  A pelvic kidney can make it more difficult to diagnose  kidney infections  and  kidney cancer . [ 4 ]  The  renal artery  and the  renal vein  may be stretched if they remain attached to the normal locations on the  abdominal aorta  and the  inferior vena cava , which can lead to illness. [ 4 ]


A pelvic kidney may increase one's risk of developing  urinary tract infections  and  kidney stones . The condition may also result in  hydronephrosis . Children with a pelvic kidney may need to wear certain protective equipment while playing sports to prevent injuries. [ 1 ]


In the development of the  human embryo , the metanephric kidneys fail to ascend and usually remain at the brim of the  pelvis . This clinical scenario may present no signs or symptoms and the kidneys may function normally. It is associated at times with  Müllerian dysgenesis . [ citation needed ]


A pelvic kidney is discovered on newborn kidney  ultrasound screening . It may also be detected if complications arise later in life for this or a completely different reason, and during investigations. [ citation needed ]


Between 1 in 2,200 and 1 in 3,000 people may have a pelvic kidney. [ 2 ]


A pelvic kidney is also known as an ectopic kidney. [ 4 ]


Penile pain  refers to pain in the  penis  of  human  or otherwise.


Priapus , a minor  Greek  god of fertility, [ 1 ]  is marked by his oversized, permanent  erection , which gave rise to the medical term  priapism .


The  perimetrium  (or  serous coat of uterus ) is the outer  serosal  layer of the  uterus , derived from the  peritoneum  overlying the  uterine fundus , and can be considered a  visceral peritoneum .  It consists of a superficial layer of  mesothelium , and a thin layer of  loose connective tissue  beneath it.


Anteriorly, the perimetrium covers the fundus and upper body of the uterus until it meets the superoposterior surface of the adjacent  urinary bladder , resulting in a concave fold of peritoneum called the  vesicouterine pouch .  Posteriorly, the perimetrium covers the entire surface of the uterus deep down to the  cervix , where it then folds back onto the adjacent  rectum  to form the  rectouterine pouch , the lowest gutter of the  peritoneal cavity .  Laterally, the perimetrium blends into the  serosae  of the  broad ligaments . [ 1 ] [ 2 ]


The  perineal raphe  is a visible line or ridge of tissue on the body that extends from the  anus  through the  perineum  to the  scrotum  (male) or the  vulva  (female). It is found in both males and females, arises from the fusion of the  urogenital folds , and is visible running medial through anteroposterior, to the anus where it resolves in a small knot of skin of varying size.


In males, this structure continues through the midline of the scrotum (scrotal raphe) and upwards through the posterior midline aspect of the  penis  ( penile raphe ). It also exists deeper through the scrotum where it is called the  scrotal septum .  It is the result of a  fetal  developmental phenomenon whereby the scrotum and penis close toward the midline and fuse. [ 1 ]


This article incorporates text in the  public domain  from  page 1237  of the 20th edition of   Gray's Anatomy   (1918)


The  perineal sponge  is a spongy cushion of  tissue  and  blood vessels  found in the lower  genital area  of  women . It sits between the  vaginal opening  and  rectum  and is internal to the  perineum  and  perineal body . [ citation needed ]


The perineal sponge is composed of  erectile tissue ; during  arousal , it becomes swollen with  blood  compressing the outer third of the vagina along with the  vestibular bulbs  and  urethral sponge  thereby tightening the vagina and increasing stimulation for the vagina and a penis, if involved. [ 1 ]


The perineal sponge is erogenous tissue encompassing a large number of  nerve endings , and can, therefore, be stimulated through the back wall of the  vagina  or the top wall of the rectum. [ 2 ]


Perinephritis  is an infection of the surroundings of the kidney either right or left. It can be the result of extravasated infiltration of the bacteria out of the renal pelvis ( pyelonephritis ) or a result of another kidney infection. The consequences include the infection of the neighbouring organs (for example  transverse colon [ 1 ] ) or  retroperitoneum , and/or  hypertension . [ 2 ] [ 3 ] [ 4 ]   Perirenal abscess  also may occur. [ 3 ]


The  pre-prostatic urethra  is one of the four parts of the  male urethra . The pre-prostatic urethra is also known as the intramural urethra, as it is the portion of the  urethra  which passes almost vertically through the wall of the  urinary bladder , before it enters the  prostate  gland.


Both the length and diameter of the pre-prostatic urethra vary depending on whether the bladder is filling or emptying. The length varies between 0.5 cm and 1.5 cm. [ 1 ]


The  prostatic ducts  (or  prostatic ductules ) open into the floor of the  prostatic portion of the urethra , and are lined by two layers of  epithelium , the inner layer consisting of columnar and the outer of small cubical cells.


Small  colloid  masses, known as  amyloid  bodies are often found in the gland tubes.


They open onto the  prostatic sinus .


This article incorporates text in the  public domain  from  page 1253  of the 20th edition of   Gray's Anatomy   (1918)


On either side of the  urethral crest  is a slightly depressed  fossa , the  prostatic sinus , the floor of which is perforated by numerous apertures, the orifices of the  prostatic ducts  from the lateral lobes of the  prostate .


This article incorporates text in the  public domain  from  page 1234  of the 20th edition of   Gray's Anatomy   (1918)


The  prostatic urethra ,  the widest and most dilatable part of the  urethra  canal, is about 3 cm long.


It runs almost vertically through the prostate from its base to its apex, lying nearer its anterior than its posterior surface; the form of the canal is spindle-shaped, being wider in the middle than at either extremity, and narrowest below, where it joins the  membranous portion .


A transverse section of the canal as it lies in the  prostate  is horse-shoe-shaped, with the convexity directed forward.


The keyhole sign, in ultrasound, is associated with a dilated bladder and prostatic urethra.


A  prosthetic testicle  is an  artificial replacement  for a  testicle  lost through  surgery  or  injury. Consisting of a plastic ovoid manufactured from  silicone rubber , and either solid, or filled with a  salt solution  and implanted in the  scrotum , a prosthetic testicle provides the appearance and feel of a  testis  and prevents  scrotum  shrinkage. It is also commonly used in  female-to-male sex reassignment surgery . [ 1 ] [ 2 ] [ 3 ]


The list shows testicular implants available in the market in 2020. [ 4 ] [ 5 ] [ 6 ] [ 7 ] [ 8 ]


Pseudodyssynergia  (or  detrusor sphincter  pseudodyssynergia) is an  urological  condition involving contraction of the  male  or  female external sphincter  during  voiding . [ 1 ]


Coordination between the sphincter and  detrusor  is thus lost. [ 2 ]


The  renal columns ,  Bertin columns , or  columns of Bertin , a.k.a.  columns of Bertini  are extensions of the  renal cortex  in between the  renal pyramids . They allow the cortex to be better anchored. (Cortical extensions into the medullary space.)


Each column consists of lines of blood vessels and urinary tubes and a fibrous material.


A hypertrophied renal column (or  renal pseudotumor ) may be differentiated from an actual  renal tumor  with the help of a  DMSA scan . The scan will show the area as one with normal activity if it is a pseudotumor or will show decreased uptake if it is a cystic or solid renal mass.


The  renal cortex  is the outer portion of the  kidney  between the  renal capsule  and the  renal medulla . [ 1 ]  In the adult, it forms a continuous smooth outer zone with a number of projections ( cortical columns ) that extend down between the  pyramids . It contains the  renal corpuscles  and the  renal tubules  except for parts of the  loop of Henle  which descend into the  renal medulla . It also contains blood vessels and  cortical collecting ducts .


The renal cortex is the part of the  kidney  where  ultrafiltration  occurs. [ 2 ]   Erythropoietin  is produced in the renal cortex. [ 3 ]


The  renal hilum  or  renal pedicle  is the recessed central fissure of the  kidney  where its vessels,  nerves  and  ureter  pass. The medial border of the kidney is concave in the center and convex toward either extremity; it is directed forward and a little downward. Its central part presents a deep longitudinal fissure, bounded by prominent overhanging anterior and posterior lips. This fissure is a  hilum  that transmits the vessels, nerves, and ureter. From anterior to posterior, the  renal vein  exits, the  renal artery  enters, and the  renal pelvis  exits the kidney.


On the left hand side the hilum is located at the  L1 vertebral  level and the right kidney at level L1-2. The lower border of the kidneys is usually alongside L3.


The superior, middle, and inferior vessels enter or leave the hilum of kidney: from anterior to posterior is renal vein, renal artery and renal pelvis, respectively.


This article incorporates text in the  public domain  from  page 1219  of the 20th edition of   Gray's Anatomy   (1918)


Renal segmental hypoplasia   is a kidney with a partially developed or  atrophic   renal cortex . [ 1 ]


Ask-Upmark kidneys are a cause of  secondary hypertension  that can be curable. [ 2 ]


It is thought to be  congenital  or the consequence of  vesicoureteral reflux . [ 2 ]
in IVU "Slit scar" is seen.


The  renal sinus  is a cavity within the  kidney  which is occupied by the  renal pelvis ,  renal calyces , blood vessels, nerves and fat. The renal hilum extends into a large cavity within the kidney occupied by the renal vessels, minor renal calyces, major renal calyces, renal pelvis and some  adipose tissue . [ 1 ]


The  rete testis  ( / ˈ r iː t i   ˈ t ɛ s t ɪ s /   REE -tee  TES -tis ;  pl. :  retia testes ) is an  anastomosing  network of delicate  tubules  located in the hilum of the  testicle  ( mediastinum testis ) that carries  sperm  from the  seminiferous tubules  to the  efferent ducts . It is the  homologue  of the  rete ovarii  in females. [ 1 ]  Its function is to provide a site for fluid reabsorption.