Question

Why do large number of follicles degenerate during phase from birth to maturity?

Answer 1

Dear student,

After the multiplication phase of oogenesis (occurs in the foetus itself), where a couple of million egg mother cells or oogonia in each ovary of the foetus are formed, it is followed by growth phase. In the growth phase, the oogonium grows into a large primary oocytes. Each primary oocyte then gets surrounded by a layer of granulosa cells to form primary follicle. A large number of these follicles degenerate during the period from birth to puberty. So at puberty only 60,000- 80,000 primary follicles are left in each ovary. This process is called as atresia of the follicles, which is mainly involution of the follicles which are immature and are poorly nutritioned. Thus, many atretic follicles occur in the ovary before puberty and in the sexually mature woman, several are formed each month. An ovum is released from the ovary in the secondary oocyte stage, from the mature follicle,during each menstrual cycle and the rest immature undergo atresia.

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