What is spermatogenesis Briefly describe the process of spermatogenesis?

Answer 1

Spermatogenesis is the process by which the male produces haploid gametes or sex cells (spermatazoa). Here is an explanation of spermatogenesis in humans.

* Spermatogenesis occurs in the seminiferous tubules of the testes in males. * Germinal epithelium gives rise to spermatagonia which are diploid (2n) and thus have 2 sets of chromosomes. * The spermatagonia then increase in size to form primary spermatocytes. * Primary spermatoctes undergo the first meiotic division and secondary spermatocytes are formed. * Secondary spermatocytes undergo another meiotic division to form 4 haploid spermatids.

* Spermatids must undergo a stage of metamorphosis before they become mature spermatazoa. This metamorphosis stage is called spermiogenesis. * During spermiogenesis, the spermatids undergo a change in shape, the cell elongates and the activity of the Golgi apparatus increases and there is production of many granules containing enzymes which are stored in the acrosome and are essential to the process of fertilisation. * One of the centrioles forms the basis from which the spermatazoa's flagellum (or tail) arises, which is required for the propulsion of sperm. * Mitochondria congregate in the neck region of the sperm and produce ATP by aerobic respiration. This ATP is needed for movement of the spermatazoa. * The nucleus also enlarges in this stage and cytoplasm is extruded into the Sertroli cells (Sertoli cells are associated with spermiogenesis). * The spermatazoa is now mature. Having said that, when newly ejaculated, sperm are not able to fertilise the female's oocyte - it is only after capacitation that the sperm is able to fertilise, and this takes place in the uterus and oviducts.