Ultrastructure of the spermatozoon of Taeniarhynchus saginatus (syn. Taenia saginata) (Goeze, 1782) Weinland, 1858 (Cestoda, Taeniidae) an intestinal parasite of human.

The mature Taeniarhynchus saginatus spermatozoon exhibits an apical cone of electron-dense material and one helicoidal crest-like body roughly 50 nm thick. The axoneme is of the 9 + "1" Trepaxonemata pattern. It is surrounded by a periaxonemal sheath of electron-dense material. The cytoplasm is electron lucent and divided into compartments by intracytoplasmic walls of electron-dense material in regions III and IV. The nucleus is an electron-dense cord 60-90 nm thick coiled in a spiral around the axoneme. It reaches the posterior extremity of the gamete where the axoneme is disorganized and is accompanied on all its posterior length by the nucleus. To our knowledge, such a posterior extremity has never been described before in a cyclophyllidean cestode.