What EXACTLY happens when an egg and sperm fuse?
821921
I like to describe things very clearly usually, you can check out my answers.  But I'm too tired to go into any more detail than the person who posted on wikipedia, so here you go.\n\nhttp://en.wikipedia.org/wiki/Acrosome_reaction
495331
with sperm i think........i dont know
910277
well, for one, males shouldn't have to produce so much sperm to fertilize one egg. During ejackulation, thousands of sperm are released. It could be refined to release fewer to maximize potential of the sperm
343457
During a vasectomy, the vas deferens from each testicle is clamped, cut, or otherwise sealed. This prevents sperm from mixing with the semen that is ejaculated from the penis. An egg cannot be fertilized when there are no sperm in the semen. The testicles continue to produce sperm, but the sperm are reabsorbed by the body. (This also happens to sperm that are not ejaculated after a while, regardless of whether you have had a vasectomy.)
983124
4)  The sheet absorbs the energy of the egg in motion.  The basic principle of action/reaction can be applied here.  The egg does not break because the accelleration is different.  When it hits the wall it decellerates quickly and the energy is put into the shattering of the egg.  When it hits the sheet the energy is absorbed by the motion of the material.
404721
It depends on the organism.  Humans are just built that way.  Other species like frogs continually generate oocytes (the egg precursor).  What happens in humans is usually not an absolute truth for other animals.  Some animals are asexual (no sperm needed).  All sorts of variations on the theme exists.
878793
I'm not quite sure I understand... but when something is fertilised internally, it's fertilised within a body. When it's fertilised externally, the eggs are outside the body and the male spreads his sperm over the eggs.\n\nInternal development would be when the embryo develops inside the mother's body. External development would be when the embryo develops in an egg or something.
890847
Fertilization, because one allele from each mate is coming together.
761650
I dont know much cuz im just in high school and not pro but heres my understanding:\nLets begin with the possibilities. Two sperm cells cleary would not work cuz of the YY issue and that wouldn't techniquelly be human anymore. However, in the female XX would be human. problem is The egg cell has a jelly coat whihc protects it. The one sperm cell that fertilizes uses enzymes to digest it away and the sperm cell must bind to a receptor site. Since we know very little about the protein world and how these receptors exactly work, just like we dont know how EXactly carrier proteins work in plasma membranes, its difficult to figure how to do it. Since implanting and fusing the two nuclei of the eggs would not initiate these receptor cyets, the zygote may not necessarly divide. It would just be a mutated egg like before and a sitting duck. You wouldn't get mitosis since it still techniquelly thinks its a gamete and wouldn't replicate. Also, too my understanding, the egg and sperm nuclei are drastically different in size and also chemical makeup may vary.Thats my assesment of the situation. Again, I'm not an expert but i think that might be enough to answer the question.
1011688
Ovulation is the release of a oocyte (precursor to a egg cell) from the ovaries to fallopian tubes. Within the fallopian tubes the oocyte is fertilized and becomes a ovum which in turn becomes a zygote and then a fetus. \n\nWhen one is pregnant hormone levels are kept at high levels which prevents the events which trigger ovulation.\n\nThis makes sense because the mother already has a fertilized egg and must now concentrate her resources to the developing fetus. \n\nIf estrogen and progesterone levels drop it will cause FSH and LH (these are all hormones) levels to rise and begin the cycle again. If this occurs it can result in a spontaneous natural abortion of an already fertilized zygote.
571791
It is medically possible at this point in time. A fertilised human egg (that has already made contact with sperm) is frozen while it is still a single cel and hasn't duplicated. Under a microscope scientists insert a needle and remove the cell nucleus that contains the DNA of the merged egg and sperm. They then insert a nucleus from the host person that contians their own DNA. The cell is then allowed to divide and continue growing, at the right time it would be placed within a surrogate mother like test tube babies until a baby is born with the exact DNA of the host person. Barring developments later in gestation such as the mother's diet and condition, the child will be an exact duplicate of the host who's DNA was used, until social factors kick in
27952
That depends on a few factors:\n\n1) Where did the sperm start?  For a sperm, a couple inches can take a while.\n2) Where is the egg?  Did the woman ~just~ ovulate, or is the egg almost to the womb?\n3) How healthy are the sperm?  Has the man ejaculated in the past few days?  Has it been more than 2 weeks?  If left in the testis too long, sperm will deform and lose motility.\n\nThe text book answer is anywhere from 4 hours to 72 hours.  Really, it depends on the above.
494504
b)Unique to Angiosperms, flowering plants exhibit double fertilization whereby two sperm nuclei are deposited in the female gametophyte with each undergoing a fertilization event. The first sperm nucleus undergoes fusion with the egg cell nucleus forming the zygote while the second sperm nucleus undergoes fusion with the two polar nuclei of the central cell resulting in a triploid cell that proliferates through mitosis giving rise to the endosperm. The endosperm is often a source of nutrition for the developing embryo after fertilization and is often a starchy tissue.
366694
this is not dangerous and it means that you have not released your sperm for awhile.  this will change back to normal when you release it regularly.  when i was younger (like when i was a teenager) this happened to me several times and now i wish that this will happen to me again.\n\np.s.\nwhy did some people answer this question just to say things like 'gross'.  if they dont like the question, just go to other questions, right?
398600
Yes, Two sperms can fertilize a egg, but it would lead to a gestational trophoblastic neoplasia \n\nGestational trophoblastic neoplasia (GTN) can be benign or malignant. Histologically, it is classified into a hydatidiform mole, an invasive mole (chorioadenoma destruens), choriocarcinoma, and a placental site trophoblastic tumor (PSTT). Hydatidiform mole is the most common form of GTN\n\n    * A hydatidiform mole occurs when a haploid sperm fertilizes an egg that has no maternal chromosomes and then duplicates its chromosomal complement.\n\n          o Most complete hydatidiform moles are 46,XX, and all the chromosomes come from the male.\n\n          o Of hydatidiform moles, 10-15% are 46,XY. This occurs when 2 sperm, 1 carrying an X and the other carrying a Y, fertilize an “empty” egg.\n\n    * Partial moles are 69,XXY, and 2 sets of chromosomes are of paternal origin.\n-----------------------------------------------------------\nFACTOR PREVENTING ENTRY OF SPERM(s) AFTER FERTILIZATION:\n\nThe Zona Reaction\n\nThe zona reaction refers to an alteration in the structure of the zona pellucida catalyzed by proteases from cortical granules. The critical importance of the zona reaction is that it represents the major block to polyspermy in most mammals. This effect is the result of two measurable changes induced in the zona pellucida:\n\n   1. The zona pellucida hardens. Crudely put, this is analogous to the setting of concrete. Runner-up sperm that have not finished traversing the zona pellucida by the time the hardening occurs are stopped in their tracks.\n\n   2. Sperm receptors in the zona pellucida are destroyed. Therefore, any sperm that have not yet bound to the zona pellucida will no longer be able to bind, let alone fertilize the egg.
616416
Sperm and Egg cells are different in a number of ways:\n1. They are haploid cells: that is, they have half the normal number of chromosomes;\n2. They are formed from meiosis: this is the immediate cause of #1;\n3. They are formed from spermatocytes and oocytes\n4. They can create a new member of their species.
145144
The shell covering an egg is porous !!.It allows Oxygen to enter into the egg and CO2 to move out of the egg!