CHANGES IN THE NUCLEUS, ENDOPLASMIC-RETICULUM, GOLGI-APPARATUS, AND ACROSOME DURING SPERMIOGENESIS IN THE WATERSTRIDER, GERRIS-NAJAS DEG (HETEROPTERA, GERRIDAE)

During spermiogenesis in Gerris najas (Heteroptera : Gerridae), wide tubules of endoplasmic reticulum are closely associated with the trans-tubular network of the Golgi apparatus. This relationship, formerly observed in spermatocytes of this species, exists also in spermatids almost from the beginning to very late stages. Different functions of the Golgi apparatus can be distinguished. At the time the acrosomal vesicle is formed, unusually large multivesicular bodies originate within the Golgi apparatus. Morphogenetic transformation of the acrosome from a huge sphere, measuring about 6.5 mum in diameter, to a long (2.5 mm) needle-like structure, is a very complicated process, during which cytoplasmic components become incorporated into the definitive acrosome.