oogenesis

oogenesis

Egg formation and maturation that begins in the fetus

oogonia

Immature egg cells that multiply by mitosis until the fifth fetal month. It produces about 6-7 million germ cells that will develop into primary oocytes.

primary oocytes

Most of the primary oocytes will die before birth. There are usually only about 400 thousand left at puberty because they continue to degenerate. Only about 400 egg cells will actually mature during their life

Primary oocytes and follicles during reproductive years

During the reproductive years 10-20 primary oocytes and follicles begin to develop each month. Normally just one of these reaches maturity and ovulates. As follicle cells develop, the egg develops within them under the influence of LH and FSH. egg undergoes meiosis but stops as a secondary oocyte until fertilization occurs.

secondary oocytes

The stage of oocyte development that occurs after the first meiotic division, typically released during ovulation and remains arrested until fertilization.

menopause

state where there are very few primary follicles left in the ovaries.