Oogenesis

Oogenesis is the process of development of the female gamete or ovum or egg in the ovaries. During foetal development, certain cells in the germinal epithelium of the foetal ovary divide by mitosis and produce millions of egg mother cells or oogonia . No more oogonia are formed or added after birth. The oogonial cells start dividing and enter into Prophase I of meiotic division I to form the primary oocytes which are temporarily arrested at this stage.

The primary oocytes then get surrounded by a single layer of granulosa cells to form the primordial or primary follicles (Fig. . a) . A large number of follicles degenerate during the period from birth to puberty, so at puberty only , to , follicles are left in each ovary.

Head Middle piece Tail Acrosome Nucleus Neck Mitochondria