Human Oogonia Atresia

In humans, the oogonia divide rapidly by mitosis from the 2nd to 7th month of gestation to produce approx. 7 million oogonia. After the 7th month, the number of germ cells drops precipitously. Most of the oogonia become atretic and die. The surviving cells enter prophase of meiosis and become Primary Oocytes. They progress to the diplotene stage of prophase and arrest there until puberty. After puberty a few oocytes resume meiosis every 28-29 days. Some oocytes are maintained in meiotic prophase for 50 years.