1.Gametogenesis is the process of producing gametes (sperms and ova by the testis and ovary, respectively).
It is of the following two types:
(i)Spermatogenesis
(ii)Oogenesis
2.Spermatogenesis is production of sperms in males.
(i) In testis, the immature male germ cells (spermatogonia) produce sperms by spermatogenesis that begins at puberty.
(ii)Spermatogonia (sing, spermatogonium) present on the inside wall of seminiferous tubules multiply by mitotic division and increase in numbers.
(iii) Each spermatogonium is diploid and contains 46 chromosomes. Some of the spermatogonia called primary spermatocytes periodically undergo meiosis.
- Male Gametes may produce 400,000,000 per day
3.Oogenesis is the process of formation of a female gamete or ova in the ovary.
(i)It starts during embryonic stage in a female.
(ii)About a million oogonia are formed in the ovary of the female foetus (of 25 weeks). No new oogonia are formed after birth.
(iii)The oogonial cells start meiotic division, enter into prophase-I, get temporarily arrested at that stage and are called as primary oocytes.
(iv)Each primary oocyte then gets surrounded by a layer of granulosa cells called primary follicle.
(v)A large number of primary follicles degenerate during the phase from birth to puberty. As a result, about 60,000-80,000 primary follicles are left in each ovary at puberty.
