Gonadal cell apoptosis: hormone-regulated cell demise

Introduction 103 Molecular mechanism of apoptosis 104 Cell depletion in the gonads 105 Detection and localization of apoptosis in the gonads 105 Hormonal control of gonadal cell apoptosis 106 Comparison of ovarian and testicular cell apoptosis 112 Conclusion 113 Acknowledgement 114 References 114 It has become evident that apoptosis, an active form of cell 'suicide', plays an important role in the normal function of all tissues. A balance of cell proliferation and apoptosis is maintained in a healthy individual and any imbalance of the two processes could lead to pathological changes. In both sexes, massive apoptosis accounts for the demise of a majority of gonadal cells (ovarian granulosa cells and male germ cells) during reproductive life. Recent studies have indicated the important role of gonadotrophins as survival factors in both the ovary and the testis. Furthermore, intragonadal survival factors in the ovary (oestrogens, insulin-like growth factor I, epidermal growth factor, basic fibroblast growth factor, interleukin-1, nitric oxide, etc.) and testis (androgens) have been shown to act in concert with the gonadotrophins. In contrast, several apoptotic factors (androgens, gonadotrophinreleasing hormone-like peptide and interleukin-6) may be important in inducing the demise of ovarian follicles. Understanding of the hormonal and cellular mechanisms responsible for gonadal cell apoptosis will provide new approaches for the treatment of gonadal degenerative conditions such as premature ovarian failure and cryptorchidism, as well as for the design of new contraceptive approaches.