Fine structure of the seminiferous tubule of the swiss mouse. The spermatid

Abstract

Abstract Electron micrographs from this study demonstrate several stages in the formation of the nuclear cap and acrosome by the Golgi system. Formation of small vesicles from Golgi membranes, coalescence of these vesicles into the nuclear cap with concomitant fusion of contained granules to form the acrosome, is confirmed. Mitchondria, which at low magnifications appear to be “empty,” are shown by high magnification to contain dilated intracristal spaces. In many cases cristae are arranged parallel to the mitochondrial surface. In later spermiogenesis, appearance of the caudal sheath or manchette, proximal centriole, and terminal annulus (“ring centriole”) precede formation of the middlepiece and flagellum. The presence of a series of parallel “annulated” membranes has been described. The exact nature of these membranes, which appear to connect with the cisternae of the endoplasmic reticulum, remains to be investigated.