Hormones and Spermatogonial Development

This chapter focuses on the effects of hormones on spermatogonial development. Two hormones, primarily T but also follicle-stimulating hormone (FSH), are required for the complete process of spermatogenesis in normal animals. Deprivation of T and FSH in rats and mice also reduces the numbers of spermatocytes and round spermatids to levels dependent on the residual concentrations of these hormones. The effects of T and FSH deprivation on spermatogonial numbers in rodents are moderate. In contrast, in adult primates (both human and monkey), the deprivation of these two hormones, especially FSH, primarily affects the conversion of type A pale to B spermatogonia, resulting in 90% reductions in B spermatogonial numbers, but there are only minor losses in the development of these B spermatogonia to spermatocytes and spermatids. The recovery of spermatogenesis in rats can be stimulated with hormone treatment given after irradiation, reversing the proliferation apoptosis (PAp) block to spermatogonial development. FSH can also inhibit spermatogonial differentiation in the models with a hormone dependent PAp block. © 2005