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.
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
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
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