how microsporogenesis is done in pearl millet?
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Try reading this. Seems microsporogenesis does not occur in apomictic pearl millet ...
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its a wonder\n\n!\n\nto know it\nThe seeds are carried away from the mother plant by animals called dispersers. In some cases the animal carries away an entire fruit, in other cases the animal is carrying seeds alone. The animal usually feeds on the fruit (ovary wall), but "tosses" the seeds (or passes them through its digestive system). This assures that seeds end up far away from the "mother" plant, where they can develop without competition from "mom."\n\nHaving been taken away from the parent, it is time for the seeds to sprout or germinate. Seed germination is defined as the emergence of the radicle through the seed coat. Common garden seeds germinate if given just water and reasonably warm temperatures.\n\nWild species usually have some kind of deeper dormancy to avoid sprouting in late summer or fall when the seeds are commonly dispersed. This assures that tender seedlings are not frozen at a young age by the approaching winter. Instead the seedlings do not appear until warm weather arrives in springtime.\n\nIf a species has evolved a very thick seed coat, it may require scarification of that seed coat before water can enter the seed and initiate germination. Perhaps the coat has to be gnawed at by animals, or frozen and thawed repeatedly to crack the coat, or rund down the rocks in a stream bed or up beach in pounding surf to wear the coat down. Perhaps the seed is swallowed whole by the disperser. The thick seed coat protects the dormant embryo as it passes through the animal's digestive system. The weakening of the seed coat through digestion means that the seed is ready to sprout when it gets deposited (along with a bit of fertilizer) by the disperser somewhere new in the environment. Yet other seeds require a brief exposure to fire to scarify the seed coat.\n\nIn species with thin seed coats, light may be able to penetrate into the dormant embryo. The embryo may then either use the presence of light or the absence of light to trigger its germination process. Small seeds with thin seed coats are likely to use light as a signal for germination. If these are buried shallowly enough for light to hit the seed, then its germination will initiate and before it runs out of reserves, its cotyledons will be doing photosynthesis. If the small seed is deeply buried it does not germinate; it has no idea how deep it is buried and may not have sufficient reserves on board to make it to the surface before they run out. Evolution favors shutting down germination in the dark for those species. For large-seeded species, the opposite may be true. There is an advantage to having your reserves buried before starting to germinate...otherwise the sprout just acts as a flag to say..."come and eat my nutritious seeds here on the surface." Evolution favors a large seed with lots of investment in storage to wait until it is buried before sending up its shoot. Such a seed will key in on darkness rather than light. In laboratory you will see an example of each of these kinds of evolutionary adaptations!\n\nIn yet other species, the embryo is fully developed when the seeds are dispersed. They need to be deposited in soil that possesses fungi that serve as host to the seed and seedling until the development is completed and the seedling is big enough to grow on its own. Trying to sprout many orchid seeds in common garden soil is futile...the required fungal hosts are not present...so leaving wild orchids where they naturally grow is the best idea.\n\nIn most species of wild plants the mother invests the seed with abscisic acid. This hormone makes the embryo dormant until environmental conditions and native enzymes permit the abscisic acid to be broken down inside the embryo. The enzyme required is present in the embryo in the fall, but it is inactive until activated by low temperature. About four weeks at 4°C is required to activate the enzyme and degrade all the abscisic acid in the embryo. This cold
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(for animal cells..)\n1. non-kinetochore microtubules lengthen. this elongates the cell even more than before.\n2. pairs of sister chromosomes attach at opposite ends of the cell.\n3. new nuclear envelopes form around the two sets of dna at the opposite ends of the cell.\n4. cytokinesis (division of cytoplasm) occurs and the plasma membrane re-forms around the two daughter cells.
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Plant cells do not form centromeres.
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It's an oversimplification to say that pollen is a plant's sperm:\n\nPollen grains are structures that house the male gametophyte generation of angiosperms and gymnosperms (seed plants).  They are also the vehicles in which the male gamete genetic code is carried to the female gamete.  Pollen grains develop in the anther in angiosperms.  It travels and is deposited on the stigma of a receptive flower.  In gymnosperms, pollen develops in the male cone, travels, and fertilizes the ovules in the female cones to produce seeds.  Each pollen grain consists of the two celled male haploid plant enclosed in a thickened wall.
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Formation of a cell wall is a characteristic feature of all plant cells.Its formation in angiosperms does not differ much from its formation in other plants cells.\n After the nuclear division is over (end of karyokinesis)only then the division of cytoplasm(cytokinesis) begins.\n A number of microtubules are laid across the original cell, equidistant from the two recently formed daughter nuclei. They fuse to form middle lamella.This is the first dividing boundery between the two cells. Deposition of cellulose now begins on this middle lamella from either side and the wall formation is completed. Thus, a cell wall in plant cells is by and large made up of a complex carbohydrate called cellulose and in between the two layers of cellulose there is a layer called middle lamella.It is like butter sandwich. Just as the layer of butter holds the two slices of bread together or just as the layer of cement holds two adjecent bricks together and forms a wall; like wise the middle lamella holds the cells together and helps to form a tissue.
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Plants - pollen (male) and ovule (female)\n\nAnimals - sperm (male) and ovum (female)\n\n.
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meiosis steps\n1) Meiosis I\nProphase I\nMetaphase I\nAnaphase I\nTelophase I\n2)meiosis II\nProphase II\nMetaphase II\nAnaphase II\nTelophase II
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Nearly all animals undergo some form of sexual reproduction. Adults are diploid or occasionally polyploid. They have a few specialized reproductive cells, which undergo meiosis to produce smaller motile spermatozoa or larger non-motile ova. These fuse to form zygotes, which develop into new individuals.\n\nMany animals are also capable of asexual reproduction. This may take place through parthenogenesis, where fertile eggs are produced without mating, or in some cases through fragmentation.\n\nA zygote initially develops into a hollow sphere, called a blastula, which undergoes rearrangement and differentiation. In sponges, blastula larvae swim to a new location and develop into a new sponge. In most other groups, the blastula undergoes more complicated rearrangement. It first invaginates to form a gastrula with a digestive chamber, and two separate germ layers - an external ectoderm and an internal endoderm. In most cases, a mesoderm also develops between them. These germ layers then differentiate to form tissues and organs.\n\nAnimals grow by indirectly using the energy of sunlight. Plants use this energy to turn air into simple sugars using a process known as photosynthesis. These sugars are then used as the building blocks which allow the plant to grow. When animals eat these plants (or eat other animals which have eaten plants), the sugars produced by the plant are used by the animal. They are either used directly to help the animal grow, or broken down, releasing stored solar energy, and giving the animal the energy required for motion. This process is known as glycolysis.
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They do, too long to explain, so just copy and paste.  I hope it helps.\n\n"The male cone (microstrobilus or pollen cone) is structurally similar across all conifers, differing only in small ways (mostly in scale arrangement) from species to species. Extending out from a central axis are microsporophylls (modified leaves). Under each microsporophyll is one or several microsporangia (pollen sacs). The photo (right) shows mature male pine cones shortly after pollen release.\n\nThe female cone (megastrobilus, seed cone, or ovulate cone) contains ovules within, which when fertilized by pollen, become seeds. The female cone structure varies more markedly between the different conifer families, and is often crucial for the identification of many species of conifers, in as much as seeing the foliage alone may be insufficient to differentiate between closely related species."\n\nCheers.
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Many ways.\n\nPlants would have organelles specific to a plant and would be a rectangular shape with 2 nuclei during cytokinesis\n\nanimal would have no chroloplasts and would be oval because the nuclei push as far apart as possible and the animal cell is flexible, not rigged like a plant.
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>meiosis (mīŏ'sĭs) , process of nuclear division in a living cell by which the number of chromosomes is reduced to half the original number. Meiosis occurs only in the process of gametogenesis, i.e., when the gametes, or sex cells (ovum and sperm), are being formed. Because fertilization consists of the fusion of two separate nuclei, one from each of the sex cells, meiosis is necessary to prevent the doubling of the chromosome number in each successive generation. An ordinary body cell is diploid; i.e., it contains two of each type of chromosome. The members of each pair are known as homologous chromosomes. An ovum or sperm is haploid; i.e., it contains only a single chromosome of each type and, therefore, half the number of chromosomes of the diploid cell. When the two haploid cells fuse, the diploid number is restored, and the plant or animal growing from the fertilized egg (zygote) has the usual diploid number of chromosomes in its cells. Just before meiosis each chromosome replicates to form two identical copies in the form of strands called chromatids joined together at a point called the centromere. In the first stage of meiosis, called the reduction division, the members of each pair of homologous chromosomes lie side by side and crossing over occurs. Each member of the pair then moves away from the other toward opposite ends of the dividing cell, and two nuclei, each with the haploid number of double-stringed chromosomes, are formed. Thus at the beginning of the second meiotic sequence, called the equational division, each cell nucleus contains one chromosome from each homologous pair and each chromosome is of two strands that are identical (except where crossing over has occurred). Then the chromosomes separate into their single strands which move toward opposite ends of the dividing nucleus. The result of meiotic division is four cells, each haploid, with one chromosome of each pair.\n\n>meiosis (meye-oh-sis) \nDivision of cells in which four “daughter” cells are produced from one “parent” cell, each with half the genes of the parent. Meiosis is a key process in sexual reproduction. In the ovaries and testes, meiosis produces a great variety of sex cells (sperm and ova), because the genes of the parent cell can be split in many different ways. The sex cells combine in fertilization to produce a new individual with the full number of genes — half from each parent. Because the sex cells come in such variety, and come from two parents, there is an enormous number of possible forms for the offspring. (See chromosomes, genetics, and mitosis.) \n\n>mei·o·sis (mī-ō'sĭs)\nn., pl. -ses (-sēz').\nThe special process of cell division in sexually reproducing organisms that results in the formation of gametes, consisting of two nuclear divisions in rapid succession that in turn result in the formation of four gametocytes, each containing half the number of chromosomes that is found in somatic cells.\n\n>meiosis: \nIn biology, meiosis is the process that transforms one diploid cell into four haploid cells in eukaryotes in order to redistribute the diploid's cell's genome.\n\nMeiosis forms the basis of sexual reproduction and can only occur in eukaryotes. In meiosis, the diploid cell's genome, which is composed of ordered structures of coiled DNA called chromosomes, is replicated once and separated twice, producing four sets of haploid cells each containing half of the original cell's chromosomes. These resultant haploid cells will fertilize with other haploid cells of the opposite gender to form a diploid cell again. The cyclical process of separation by meiosis and genetic recombination through fertilization is called the life cycle. The result is that the offspring produced during germination after meiosis will have a slightly different blueprint which has instructions for the cells to work, contained in the DNA. This allows sexual reproduction to occur.\n\nBiochemically
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Easiest method involves the pooling of the source (best source is wheat germ due to ease) next grind the germ then add some detergent solution- this will lyse the cell wall (the grinding breaks down the plant wall) next is to add some form of alcohol (isopropanol or high % ethanol is best (91% Isopropanol is available at drug stores)) Add the alcohol and the DNA will float to the top with the solution- spool on a glass rod.
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Abstract \nPollen morphology is closely related to its function. Many of the features present in pollen grains have helped the species of plants to which it belongs to adapt to life on land, be able to disperse its pollen, and fertilize the female eggs to produce new seeds that would give rise to new plants.  I have collected four samples of pollen from angiosperms and studied their detailed morphology.  This paper studies the correlations between the structure and function of pollen grains of those four species angiosperms.\n\nPollen grains are structures that house the male gametophyte generation of angiosperms and gymnosperms (seed plants).  They are also the vehicles in which the male gamete genetic code is carried to the female gamete.  Pollen grains develop in the anther in angiosperms.  It travels and is deposited on the stigma of a receptive flower.  In gymnosperms, pollen develops in the male cone, travels, and fertilizes the ovules in the female cones to produce seeds.  Each pollen grain consists of the two celled male haploid plant enclosed in a thickened wall.\n\nThe casing that houses the male gametophyte has a very complex structure that is reflective of that specific species' functional adaptations.  The exine is the outer layer of a living pollen grain.  It is composed of sporopollenin, with small quantities of polysaccharides.  Sporopollenin is very chemically stable1 and it is resistant to to almost all kinds of environmental damage.  It is equipped with apertures.  It it divided into two sub layers: the outermost sexine and the unsculptured underlying nexine.  The sexine has surfaces that are sculptured in elaborate ways, with reticulately arranged perforations.  These give the exine and amorphous or granular appearance.  The inner layer of a living pollen grain is called the intine.  It is composed of cellulose and is very similar in construction to ordinary plant cell walls.  A layer called the endexine separates the sexine and intine.  The endexine has a laminated appearance.\n\nPollen grains are generally classified according to their physical appearance.  There are three criteria of classification: 1) the number and position of the apertures; 2) the shape of the pollen grain as a whole; and 3) the fine elaborate structure on the sexine.  Apertures are any missing parts of the exine, which are independent of the exine pattern.  Apertures are big and they cut across the fine structure pattern on the surface of the pollen grain.  There are two types of apertures: pori or pores are mostly isodiametric apertures, although the can be slightly elongated with rounded ends; colpi or furrows are long and boat shaped with pointed ends.  Colpi are thought to be more primitive.  In living pollen grains these apertures are not actually open.  Instead, a very thin layer of exine covers them.  Grains with pori are called porate; those with culpi are called culpate; and those with both pori and culpi are called colporate.  If their apertures are arranged equidistantly around the equator of the pollen grains they are assigned the prefix zono-; if they are scattered all over the surface of the pollen grain they are assigned the prefix panto-.  The number of apertures is also indicated by prefixes: mono- for one aperture; di- for two apertures; tri- for three apertures; and so on.\n\nThe shape of a pollen grain refers to the shape of their outline in polar and equatorial views.  The shape of a grain can sometimes be useful in identifying of pollen species, but not usually. I may vary considerably within one grain type, and sometimes within one species.\n\nThe sculpture refers to the fine structure and pattern of the sexine.  It is composed of small radially directed rods.  If these rods support something (such as a plate or a small knob) they are called columnellae; if they do not support anything they are called bacula.  The shape of the rods can further classify them.  If they are club shaped they are called clavae;
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by the name of allah\ni'm an arabian from egypt\nstudient at the last year faculty of science alazhar university\nthe spermatogenesis is the process to produce the sperm \nit started in the testis \nSpermatogenesis begins at puberty and involves mitotic proliferation, meiotic division and extensive cell modeling It starts with the spermatogonia or germinal cells dividing mitotically to produce a small clone of diploid  cells termed spermatocytes. The spermatocytes migrate through the tight junctions at the base of the Sertoli cells and, in their new environment cradled by the Sertoli cells, undergo two meiotic divisions. In the first division, pairs of chromosomes come together and exchange DNA (crossing over) and separate into two haploid cells (23X or 23Y) known as secondary spermatocytes. Almost immediately, a second meiotic division takes place in which the two chromatids that make up a single chromosome separate. These haploid cells, thus, contain 23 single half chromosomes and are called spermatids.\n\nAt this stage, they are still simple round cells but before they leave the nurturing of the Sertoli cells an acrosome (essential for fertilization) is formed at the head of the sperm and a tail develops. They are extruded from the Sertoli cells into the lumen of the seminiferous tubule. This whole process of spermatogenesis takes approximately 74 days and about 300600 sperm/gram of testis are produced each second. Not all survive.\n\nFrom the seminiferous tubules, the sperm are washed towards the rete testis which drains into the vasa efferentia and from there into the epididymis, a highly convoluted tube that finally drains into the vas deferens During the 12 day passage from the testis to the vas deferens, the sperm become motile and mature to reach full fertilizing ability. As a result of fluid absorption in the epididymis, sperm also become highly concentrated.\n\nWhilst spermatogenesis is dependent on the hormonal drive from the gonadotrophins and testosterone, temperature also plays a critical factor in this process. Normal spermatogenesis is impaired if the testis is maintained at normal body 'core' temperature (as occurs in cryptorchidism or through tight clothing). The temperature of the testes is normally maintained about 2°C lower than core body temperature because they lie outside the body, moving freely in the scrotal sac. Three layers of membranes enclose each testis and extensions of the fibrous tunica albuginea form septa that divide the gland into 200300 lobes. In appearance, the testes are white with an oval shape (approximately 4 × 2 × 3 cm with a volume of about 25 ml and weighing between 1014 g). Seminiferous tubules constitute 7080% of this mass and each testis has approximately 200 m of seminiferous tubule. The blood supply comes from the testicular arteries that are branches of the internal spermatic arteries.\n\nA fully functioning testis normally achieved by the age of 16 years has the capacity to produce over 200 million sperm each day. Only one is required for fertilization, but each tiny sperm (a few thousandths of a millimeter in length) must travel some 3040 cm (100 000 times its own length) of the male and female reproductive tract before it reaches its final destination in the Fallopian tube. Less than 1 in a million ever completes this journey, though they are helped by the process of ejaculation.\n\nClinical Case 6.6 had normal Leydig cell function but clear evidence that his Sertoli cells had been damaged resulting in loss of spermatogenesis and infertility. There are a number of causes of this  but it is highly likely given his past medical history that the cytotoxic drug cyclophosphamide was the cause. Clinical Case 6.6 underwent testing of his seminal fluid and it was found that he had azoospermia (Treatment is possible in a number of causes of male infertility  but currently there is none available for cyclophosphamide-induced azoospermia. Cryopreservation of ovary and
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diploidization\n\ndoubling of chromosome no.\nthis method is usually implied in plants to double their chromosomal configuration
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To clarify how an alien addition and substitution lines works,For it a  greenhouse bioassay was developed that consistently ranked four small grains in their correct order of susceptibility to take-all in the field (wheat > barley > rye = oat) (4). This assay was used to evaluate several wheats that carry alien chromosomes. Single plants were grown in a 1:1 (v:v) mixture of pasteurized soil (Kennebeck silty clay loam) and vermiculite in plastic tubes (2.5 cm in diameter and 12.5 cm long). Experiments included 10 tubes per entry-treatment (inoculated or non-inoculated) per replication and 4 replications. The experimental design was a randomized split-plot with the accessions as main-plot treatments and presence or absence of inoculum as sub-plot treatments .Inoculated tubes each received three oat kernels colonized by G. graminis var. tritici introduced 1 cm below seed level .After 4 weeks at 20±5°C, fresh weights of plant parts (10 plants per treatment per replication) above the soil level were measured and losses in fresh weight calculated.\nFour sets of wheat-alien chromosome addition and substitution lines of species with resistance to take-all were obtained from the Wheat .. The sets were: (i) wheat (cv. Chinese Spring)-Hordeum vulgare (cv. Betzes) disomic addition lines; (ii) wheat (cv. Chinese Spring)-Hordeum chilense disomic addition lines; (iii) wheat (various lines)-H. villosa disomic addition and substitution lines; and (iv) wheat (cv. Chinese Spring)-H. villosa disomic addition lines. Three of the four sets were not complete. Cytogenetic analysis revealed that two addition lines of Set i (chromosomes 1H and 7H) and two addition lines of Set ii (2Hch and 3Hch) had only 42 chromosomes. For Set iii, addition and substitution lines for 1V, 2V, and 7V were not available. Parental lines and "Don" oats were used as controls.Each set of addition and substitution lines, along with the appropriate controls, was evaluated in its own experiment. Within an experiment, 80 seeds of each entry (line or control) were used (10 in non-inoculated tubes and 10 in inoculated tubes in each of 4 replications). All five wheat-barley disomic chromosome addition lines were more susceptible [82 to 90% loss in fresh weight, LSD (P = 0.05) = 10.1] than the barley parent (Betzes = 36%) and two of them (2H and 3H) had significantly more loss (90%) than the wheat parent (Chinese Spring = 78%). In another experiment, there were no differences among all five wheat-H. chilense disomic chromosome addition lines [77 to 88%; LSD (P = 0.05) = 13.7] and they were as susceptible as the wheat parent (79%). In a third experiment (Set iii), H. villosa [30%; LSD (P = 0.05) = 8.16] was more resistant than barley (Betzes = 47%); however, all four wheat-H. villosa disomic chromosome addition and two substitution lines (4V and 5V) were more susceptible (85 to 93% loss) than the wheat check (76%). Substitution lines 3V and 6V were as susceptible (75 to 80%) as wheat. In a fourth experiment involving the complete set of wheat-H. villosa disomic chromosome addition lines (Set iv), improved levels of resistance over that of the wheat parent [77% loss; LSD (P = 0.05) = 14.9] were not detected in any of the chromosome addition lines (74 to 90%).In summary, the bioassay used in this study was a rapid, accurate way for screening accessions for susceptibility to take-all in the greenhouse. None of the addition or substitution lines had improved levels of resistance even though their resistant parents had significantly less take-all than wheat. In the cases where a complete set of lines was not available, any genes that might confer resistance may be on a chromosome missing from the set. Alternatively, take-all resistance in these species may be polygenic with genes on different chromosomes or it may be masked by the wheat genome. Therefore, transfer of take-all resistance from H. vulgare, H. chilense, or H. villosa to wheat may not be easily accomplished.