title: Spermiogenesis and sperm ultrastructure of the pseudophyllidean cestode Triaenophorus nodulosus (Pallas, 1781).
abstract: Spermiogenesis and ultrastructure of the spermatozoon of the pseudophyllidean cestode Triaenophorus nodulosus (Pallas, 1781), a parasite of pike Esox lucius, has been studied by transmission electron microscopy. Spermiogenesis involves firstly the formation of a zone of differentiation with two centrioles associated with striated roots, and an intercentriolar body between them, subsequent growth of the two flagella of unequal length, and a formation of a median cytoplasmic process exhibiting patches of dense material. The nucleus penetrates into spermatid body after flagellar rotation and proximo-distal fusion has started. The mature spermatozoon of T. nodulosus is filiform and contains two axonemes of 9+"1" pattern of the Trepaxonemata, nucleus, cortical microtubules parallel to the spermatozoon axis, and electron-dense granules. The anterior extremity of the gamete contains a single centriole surrounded by numerous electron-dense tubular structures exhibiting spiral arrangement and giving rise to lateral projections, which correspond to the crested body. When the crested body disappears, the spiral pattern of electron-dense tubular structures is changed into a ring, persisting until the centriole of the second axonemes appears. This structure of the crested body of T. nodulosus is unique among the Eucestoda.
authors.affiliation: Institute of Parasitology, Academy of Sciences of the Czech Republic, Branisovská 31, 370 05 Ceské Budejovice, Czech Republic. levron@paru.cas.cz
authors.forename: Céline
authors.initials: C
authors.lastname: Levron
authors.forename: Magdaléna
authors.initials: M
authors.lastname: Brunanská
authors.forename: Bernard
authors.initials: B
authors.lastname: Marchand
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000648:ultrastructure; D002502:Centrioles / Q000648:ultrastructure; D002589:Cestoda / Q000502:physiology*; D003593:Cytoplasm / Q000648:ultrastructure; D005407:Flagella / Q000648:ultrastructure; D008297:Male; D046529:Microscopy, Electron, Transmission; D008870:Microtubules / Q000648:ultrastructure; D008954:Models, Biological; D009024:Morphogenesis / Q000502:physiology; D015388:Organelles / Q000648:ultrastructure; D013091:Spermatogenesis / Q000502:physiology*; D013094:Spermatozoa / Q000648:ultrastructure*