The Regression Period (Electron Microscopic Studies)

Abstract

The results of the light microscopic studies on the single phases of an annual cycle can be confirmed by electron microscopic examinations. Since the characteristics of the different types of germ cells, as far as they can be met out of the active phase of spermatogenesis, do not change, it is not necessary to repeat the description of their ultra-structure. However, when these cells disintegrate, then their density often changes so much that certain characteristics can only be recognized and identified by means of electron microscopy (Fig. 22). With the increased appearance of degenerating germ cells, the Sertoli cells also undergo changes such as are only observed during the regression phase of the testis, on account of increased phagocytotic activity. Furthermore, only by examining the ultrastructure is it possible to characterize the transiently appearing macrophages and to trace them on their way from the interstitial tissue across the germinal epithelium. Therefore that phase in the process of involution which was decribed light microscopically as phase 4 of the annual cycle will now be described and discussed in the light of electron microscopy.