ULTRASTRUCTURE OF SPERMIOGENESIS OF DIPYLIDIUM-CANINUM (CESTODA, CYCLOPHYLLIDEA, DIPYLIDIIDAE), AN INTESTINAL PARASITE OF CANIS-FAMILIARIS

We describe for the first time the ultrastructure of spermiogenesis of a representative of the family Dipylidiidae, Dipylidium caninum. Sper miogenesis begins with the formation of a differentiation zone, This c onical area presents two centrioles with associated striated roots. On e of the centrioles develops a flagellum and posteriorly a proximodist al fusion is produced between the axoneme and a median cytoplasmic pro cess. In a final stage of spermiogenesis a condensation of electron-de nse material between cortical microtubules is observed in the anterior part of the differentiation zone, This is the origin of the crest-lik e body that appears at the end of spermiogenesis. The presence of stri ated roots associated with centrioles constitutes the first report of these structures in the spermiogenesis of a cyclophyllidean cestode. ( C) 1998 Australian Society for Parasitology. Published by Elsevier Sci ence Ltd, All rights reserved.