Aspects of ovarian follicle development throughout life

The pool of primordial follicles present in the female ovary reaches its ma ximum number around 20 weeks of gestational age and then decreases in a log arithmic fashion throughout life until complete depletion occurs around the age of the menopause. Reproductive life is initiated when less than 10% (0 .5 million) of primordial follicles are left. The entire growth trajectory of the follicle takes at least 3 months. Follicle growth up to the antral s tage occurs during fetal life and infancy. While the role of gonadotropins in early follicular development remains controversial, the last 2 weeks of development are FSH dependent. The intercycle rise in FSH and decreasing le vels thereafter are crucial for recruitment of a cohort of healthy, early a ntral follicles and subsequent single dominant selection. Following puberty , anovulation may persist for years and this may presage the development of adult anovulatory infertility. The menopause is preceded by a period of re duced fertility. The development of reliable and sensitive markers for ovar ian ageing will be the challenge of the near future. Copyright (C) 2000 S. Karger AG, Basel.