The spermatozoon of Truncatella (s.str.) subcylindrica (L.) (Gastropoda Prosobranchia)

The spermiogenesis of Truncatella (s. str.) subcylindrica (L.) (Prosobranchia, Truncatellidae) has been studied with the electron microscope. The different parts of the spermatozoon are arranged in a normal sequence but they have nevertheless, certain peculiarities which deserve attention: The nucleus is almost entirely helical; two concentric rings of microtubules are contained within the walls of the acrosomal cone the inner one reaching only half way up the cone. The «coarse fibres» present in the terminal segment of the axoneme of other kinds of Prosobranchs are not present here. Through the study of the several phases of the spermiogenesis it has been ascertained that the acrosomal cone and the acrosomal rod derive from the Golgi complex and that the classical centriole disappears after the very first phases of the spermatid’s maturation.