In amphibians the germ cells arise in the vegetal pole region whereas in mammals the cells arise in the extraembryonic yolk sac mesoderm and then must . The process of Gametogenesis is stimulated by the FSH or Follicle . eggs of shark, bony fish, Reptiles, birds, prototherian, concentrated mainly in vegetal pole . marginal zone, transitional area between animal and vegetal hemispheres. maturation, process of gaining fully differentiated form. maturation promoting factor.

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In vertebrates the first polar body is formed after the primary oocyte is released from ovary and has entered into the oviduct. The data for other farm animals, rabbit, mouse and human are depicted in Table 3.

Useful Notes on Gametogenesis (Spermatogenesis and Oogenesis)

The removal of sperm perinuclear theca and its association with the bovine oocyte surface during fertilization. Protamines are replaced by the histones generated by the oocyte. Each of these populations of spermatogenic cells will be at different stages of spermatogenesis. The egg white albumincalcareous shell etc.

Useful Notes on Gametogenesis (Spermatogenesis and Oogenesis)

The role of oocyte maturation inhibition in follicular regulation of oocyte maturation. In mammals such supporting cells are called cells of Sertoli.

Indications for aneuploidy and multinucleation. Each testis is formed of thousands of minute elongated and coiled tubules called seminiferous tubules.

Journal of Biological Sciences, 8: Small oocytes in primordial and primary follicles have no ability to resume meiosis.

Formation of MPN takes place simultaneously with disappearance of the nuclear membrane, decondensation of the chromosomes and reformation of the pronuclear membrane that is supported by action of growth factors. The first sign of morphological change when the oocyte begins agmetogenesis grow is turning of the flat GCs to cuboidal which is known as primary follicle.


Gametogenesis – Spermatogenesis – Oogenesis – TeachMePhysiology

Goat embryo production from in vitro matured heterogeneous oocytes fertilised by intracytoplasmic sperm injection ICSI technique. The spermatozoa must reside a minimum period in the female reproductive tract before gaining the ability to fertilize oocytes Austin, ; Chang, Although, AR is now considered as a separate process Bavister,which triggers after capacitation, however, discrepancies exists as some authors believe that it was a part of the capacitation process Austin and Bishop, and others considered AR as the final phase of capacitation Yanagimachi, However, for the success in any IVP protocols in goat sound knowledge of physiology of gametogenesis, fertilization and early embryogenesis in vivo is crucial because in vivo information form the basis and guide for any in vitro experiment.

Simultaneously, the first polar body may divide into two polar bodies or may not divide at all. Following penetration, the acrosome-reacted sperm passes through PVS and interacts with the sperm plasma membrane of the oocyte oolemma Schultz and Kopf, The two centrioles of middle piece develop axial filaments which are bunched into a single thread and extend behind in the form of a long vibratile tail. In vivoresumption of meiosis is initiated by a preovulatory LH surge and only occurs in fully grown, meiotically competent oocytes from dominant follicles.

Once puberty begins, a number of primary oocytes begin to mature each month, although only one of these reaches full maturation to become an oocyte.

After the embryo reaches to the morula stage it is very difficult to discern the boundaries between blastomeres as the embryo undergoes compaction in which the blastomeres flatten against each other to form intercellular junctions between them. The embryo is confined within the ZP analogous to eggshell in bird, reptiles or monotremes throughout the early stages of development.


Fertilizing capacity of spermatozoa deposited into vametogenesis fallopian tubes. Human embryos with unevenly sized blastomeres have lower pregnancy and implantation rates: In mammals, the male and female gametes originate from the embryonic yolk sac.

Schematic diagram of gametogenesis in mammals. The times required to blastocyst hatching in case of other domestic animals, rabbit, mouse and human are depicted in Table 3. If you consider that the spermatogenesis process takes a long time two months and that these cells require gene transcription for both the usual housekeeping functions of the cell and some specialized functions for making sperm then there is a problem in that the four developing gametes lack either an X or a Y chromosome.

A history of farm animal embryo transfer and some associated techniques. The plane of second division is also vertical and passes through the main axis but at a right angle to the initial plane of cleavage, resulting in 4 blastomeres.

The original can be viewed here: This is the second phase of spermatogenesis during which the spermatids produced at the end of first phase are metamorphosed into sperm cells. The spermatogonia do not divide for sometime but increase in size by accumulating nutritive materials from ggametogenesis supporting cells.

The inner lining of seminiferous tubules is called as germinal epithelium and is made of primordial germ cells Primary germ cells as well as some supporting nutritive cells. In the doe, antrum formation began when the GCs are about six cell layers in thickness and the Zona Pellucida ZP is visible at gameotgenesis stage Ariyaratna and Gunawardana,