Ultrastructural Differentiation of Rat Sertoli Cells1

Abstract

Fine structural cytodifferentiation of rat testis Sertoli cells was examined at 2 wk intervals from day 7 postnatally to sexual maturity. The cells undergo rapid morphological differentiation during the first 5 wk after birth. These changes include a large increase in cell size and in the extent of cytoplasmic processes between germinal cells. Changes occur in the pattern of nuclear chromatin condensation and nuclear envelope infoldings and in the development of cellular organelles, particularly the smooth endoplasmic reticulum, Golgi apparatus, and mitochondria. Differentiation of the basal cytoplasm primarily consists of a regional accumulation of microtubules and microfilaments, whereas apical surface specializations consist of finger-like cytoplasmic projections. An apparent sequence of events was observed in the development of the junctional complexes between neighboring cells and in the formation of the tripartite nucleolus. This Sertoli cells structural differentiation occuring during the prepuberal period correlates with the appearance of various physiologic and metabolic changes in the function of the developing testis.