The Premeiotic Stages of Spermatogenesis

Abstract

Publisher Summary The purpose of this chapter is to incorporate the information on spermatogonia into the large body of evidence on germ-cell maturation in Drosophila melanogaster to be able to relate the temporal and spatial patterns of spermatogenesis more precisely. One of the greatest impediments to an understanding of the function of the spermatogonia is the vagueness of the terminology. Two or more types of spermatogonia can readily be distinguished in the testes of many insects. In referring to the spermatogonia responsible for the maintenance of the germ line—that is, the stem-cell spermatogonia, the terms “dormant mother cell” or “dormant A-type spermatogonium” are used for the mammals. Spermatogenesis is a continuous process in which a single spermatogonium gives rise, as the result of cell multiplication and differentiation, to the primary spermatocytes, each of which in turn after an enormous increase in size and a series of complex nuclear changes, undergoes the first meiotic division to produce the secondary spermatocytes.