Oogenisis

Oogenisis

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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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Second stage of development of ovarian follicles

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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Third stage in development of Ovarian follicles

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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