ELECTRON MICROSCOPIC STUDIES ON ACHROSOME FORMATION IN THE COCKROACH, BLATTELLA GERMANICA

The development of achrosomes in spermiogenesis of Blattella germanica was studied by electron microscopy. Achrosomes consist of an achrosomal vesicle originating from Golgi vesicles and an axial rod composed of fine fibrils. The achrosomal vesicle, formed at the mature face of the Golgi body, migrates to the anterior of the nucleus, where it later becomes the front structures of sperm head. After attachment to the nucleus, the achrosomal vesicle changes from a round to a tapering shape, passing through a coneshape phase. During these changes, the axial rod develops in the hollow formed by indentations of adjacent parts of the achrosomal vesicle and the nucleus. The cisternae of the Golgi body concerned with formation of the achrosomal vesicle, are made by pinching off small vesicles from both the ER and the nuclear envelope.