Demonstration of the orientation of the Cestodes spermatozoon illustrated by the ultrastructural study of spermiogenesis and the spermatozoon of a Cyclophyllidea: Thysaniezia ovilla, Rivolta, 1874
Ba, C.T.; Marchand, B.; Mattei, X.
Journal of Submicroscopic Cytology and Pathology 23(4): 605-612
1991
ISSN/ISBN: 1122-9497 PMID: 1764687 Document Number: 379532
Spermiogenesis in Thysaniezia ovilla begins with the appearance of a differentiation zone equipped with peripheral microtubules, surrounded by arched membranes and containing two parallel centrioles surrounded by electron dense graunular material. One of the centrioles aborts, the other gives rise to a flagellum which quickly grows in the cytoplasmic extension in which the nucleus migrates and protein granules form. During the nuclear migration crested-like bodies appear among the peripheral microtubules in the differentiation zone. The T. ovilla spermatozoon is filiform. One of its extremities, which we show to be antierior, exhbiits two helicoidal crested-like bodies, surrounded by electron dense material resembling an acrosome. Cortical microtubules run along almost the whole length of the spermatozoon. The cytoplasm has no mitochondria and contains protein granules. The axonene is of the 9 + '1' pattern. It stops before reaching the posterior extremity of the gamete. The nucleus is wrapped round the axoneme, in the middle region of the spermatozoon. It generally stops before reaching the posterior extremity of the flagellum. This study has enabled us to describe precisely the orientation of the spermatozoon of cestodes in general.