OOGENESIS

Production of Ova

What is Oogenesis

The formation, development, and maturation of an ovum.

Oogenesis begins in the female embryo

Primoridal germ cells differentiate into oogoina (stem cells)

At 2 – 7 months of gestation, ~ 1000 oogonia divide to form ~ 7 million germ cells

From 7 – 9 months, most oogonia die

the remaining enter the first meiotic division

primary oocyte

 The primary oocytes remain resting within small follicles until puberty

Ovary

Process of Ovulation

Started by drop in estrogen

Signals hypothalamus to release GnRH

GnRH goes to pituitary, and it relases FSH

Increase in FSH stimulates about ~20 oocytes to mature

Meiosis I to form secondary oocyte

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One oocyte (in most cases) matures and is expelled. The others are reabsorbed before ovulation occurs

Follicle

Estrogen and progesterone are secreted by some of the cells in the follicle

Cytoplasm and nutrients

Ovulation occurs when follicle and ovarian surface open

Corpus leuteum

The empty follicle becomes the corpus leuteum

If pregnancy does not occur, it is reabsorbed

If pregnancy does occur, it produces hormones that help maintain pregnancy

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