Affiliation: | a Department of Morphology of Microorganisms and Electron Microscopy, Institute of Microbiology, Bulgarian Academy of Sciences, Acad. G. Boncehv Str., Bl. 26, 1113, Sofia, Bulgaria b Institute of Ecology, Bulgarian Academy of Sciences, Gagarin Str. 2, 1113, Sofia, Bulgaria c Institute of Experimental Pathology and Parasitology, Bulgarian Academy of Sciences, Acad. G. Bonchev. Str., Bl. 25, 1113, Sofia, Bulgaria |
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° 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 β-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. |