Oogenisis

In developing ovaries primordial germ cells produce OOGENIA until weeks 20 to 24 of pregnancy by miotic divisions

In weeks 8-9 oogonia enter PROPHASE

6 months after birth all oocytes will have matured from oogonia.

oocytes remain in a state of suspended prophase and mitosis does not occur until ovulation.

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First stage of development of ovarian follicles

very long = lasts many years

GRANULOSA cells proliferate and nuture oocyte with nutrients and steroid hormones

follicle becomes primary follicle

Granulosa cells begin to secrete fluid

No follicle progress until puberty

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occurs during each menstrual cycle

fluid containing steroid hormones mucopolypsaccharides, proteins and FSH accumulates in atrium of follicle.

Steroid hormones are secreted by GRANULOSA cells

End of second stage = Graffian follicle

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One Graffian molecule acheieves dominance and ruptures and releases its oocyte into peritoral cavity

begins second meitoic division

If fertilisation occurs -

2nd miotic division completes and haploid ovum with 23 chromosomes

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