title: Ultrastructure of spermiogenesis and the mature spermatozoon of Tetrabothrius erostris Loennberg, 1896 (Cestoda, Tetrabothriidae).
abstract: The spermiogenesis of Tetrabothrius erostris is characterized by the following events: formation of a differentiation zone containing 2 basal bodies and a pair of rootlets; one of the basal bodies gives rise to a free flagellum, the other induces formation of a flagellar bud; rotation at 90 degrees of the flagellum prior to its fusion with the middle cytoplasmic process of the differentiation zone and partial rotation of the flagellar bud; penetration of the nucleus between the rootlets and appearance of a spur-like protrusion in the differentiation zone; elongation and twisting of the differentiation zone, resulting in twisting of the peripheral microtubules and migration of the nucleus; formation of a crested body; proximal densification of the spermatozoon prior to its detachment from the spermatid rosette. The mature spermatozoon has a single axoneme of 9+"1" type and twisted peripheral microtubules. It consists of 3 portions: a proximal part with a crested body, a middle region rich in beta-glycogen, and a distal part containing the nucleus. The pattern of spermiogenesis resembles most closely that in phyllobothriid tetraphyllideans, and probably reflects a relationship of the family Tetrabothriidae with this group.
authors.affiliation: Department of Morphology of Microorganisms and Electron Microscopy, Institute of Microbiology, Bulgarian Academy of Sciences, Sofia, Bulgaria.
authors.forename: S R
authors.initials: SR
authors.lastname: Stoitsova
authors.forename: B B
authors.initials: BB
authors.lastname: Georgiev
authors.forename: R B
authors.initials: RB
authors.lastname: Dacheva
mesh_terms: D000818:Animals; D002589:Cestoda / Q000145:classification / Q000469:parasitology / Q000648:ultrastructure*; D008297:Male; D008854:Microscopy, Electron; D013045:Species Specificity; D013091:Spermatogenesis; D013094:Spermatozoa / Q000648:ultrastructure*