The molecular basis of ovarian cell death during germ cell attrition, follicular atresia, and luteolysis.

Physiological cell death mechanisms (termed apoptosis, programmed cell death, active cell death, and biological cell death) play a fundamental role in the cyclic function of the ovary as it strives in each cycle to ovulate a viable egg for fertilization. Healthy ovarian follicles and corpora lutea are also required for the secretion of steroids to prepare the female reproductive tract for embryo implantation and gestation. Using molecular biological approaches combined with classic histological examinations, several recent studies have confirmed the occurrence of apoptosis in female germ cells (oogonia and oocytes) during fetal ovarian development, granulosa cells during follicular atresia, and cells of the corpus luteum during luteolysis. Additionally, new light has been shed on the potential gene products which function to precisely coordinate the balance of life and death in the ovary. It is the purpose of this review to discuss the concepts of physiological cell death as they relate to ovarian function, and to offer testable hypotheses concerning the intracellular effector pathways responsible for directing ovarian cell fate in response to changes in hormonal stimuli.