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. Author manuscript; available in PMC: 2021 Apr 8.
Published in final edited form as: Trends Endocrinol Metab. 2016 May 21;27(7):516–528. doi: 10.1016/j.tem.2016.04.011

Figure 1. Ovarian Reserve Throughout Life, Normal Ovarian Function, And the Impact of Various Pathologies.

Figure 1

The ovarian reserve is established before birth, and thereafter the number of follicles containing the oocytes decreases through controlled atresia until menopause when the ovarian reserve is virtually exhausted. Normally, during the reproductive lifespan ovarian follicles go through distinct developmental stages and one oocyte is released monthly. However, in women with polycystic ovary syndrome (PCOS), hormonal disturbances result in follicular arrest and anovulation, while in premature ovarian insufficiency (POI) the ovarian reserve is depleted prematurely. During ovarian stimulation (COS) used for in vitro fertilization (IVF), exogenous hormones are used to stimulate the growth and release of several oocytes.