a1 Institute of Anatomy, University of Münster, Vesaliusweg 2–4, W–4400 Münster, Germany
a2 Institute of Physiology, Ruhr-University Bochum, W–4630 Bochum, Germany
The ultrastructure of the spermatid and spermatozoon of Macracanthorhynchus hirudinaceus (Archiacanthocephala) was studied by means of transmission electron microscopy. The flagellum and nucleus in the spermatid gradually expanded simultaneously. The karyoplasm of the spermatid transformed into dense inclusions and a multibarrel structure, which were also found in the spermatozoan body. The multibarrel structure was located close to the flagellum and consisted of many irregular microtubes. The flagellum of the developing spermatozoon was observed in a concavity of the spermatid nucleus. The microtubule arrangement of the flagellum was ″9+2″. No mitochondria or acrosome were observed in spermatozoa.
(Accepted August 12 1992)