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Gametogenesis is a biological process by which diploid or haploid precursor cells undergo cell division and differentiation to form mature haploid gametes. Depending on the biological life cycle of the organism, gametogenesis occurs by meiotic division of diploid gametocytes into various gametes, or by mitotic division of haploid gametogenous cells. The gametophytes grow from haploid spores after sporic meiosis.
However, before turning into gametogonia, the embryonic development of gametes is the same in males and females.
Gametogonia are usually seen as the initial stage of gametogenesis. However, gametogonia are themselves successors of primordial germ cells. During early embryonic development, primordial germ cells (PGCs) from the dorsal endoderm of the yolk sac migrate along the hindgut to the gonadal ridge. They multiply by mitosis and once they have reached the gonadal ridge in the late embryonic stage, they are called gametogonia. Gametogonia are no longer the same between males and females.
From gametogonia, male and female gametes develop differently - males by spermatogenesis and females by oogenesis. However, by convention, the following pattern is common for both:
|gametogonium||diploid/46||2N before replication, 4N after it||gametocytogenesis (mitosis)|
|primary gametocyte||diploid/46||2N before replication, 4N after it||gametidogenesis (meiosis 1)|
|secondary gametocyte||haploid/23||2N||gametidogenesis (meiosis 2)|
Physiology, endocrinology, sex: Reproductive physiology and endocrinology
|Menstrual cycle/Estrous cycle|
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