Ultrastructure of the spermatozoon of Anomotaenia quelea (Mettrick, 1961) (Cestoda, Cyclophyllidea, Dilepididae), an intestinal parasite of Quelea quelea (Aves, Ploceidae) in Senegal

Spermatological Characterization of the Cestode Meggittina gerbilli (Cyclophyllidea: Catenotaeniidae), a Parasite of Gerbils, Gerbillus gerbillus and Gerbillus campestris (Rodentia: Muridae) in Tunisia

Ultrastructural characters of spermiogenesis and the mature spermatozoon of the cestode Meggittina gerbilli (Cyclophyllidea: Catenotaeniidae), a parasite of the Lesser Egyptian gerbil (Gerbillus gerbillus) and the North African gerbil (Gerbillus campestris) (Rodentia: Muridae) in the Djebel Dahar (South of Tunisia), were studied using transmission electron microscopy. The spermiogenesis of M. gerbilli is of Bâ and Marchand's type III, which is mainly characterized by a proximodistal fusion of a single flagellum with a cytoplasmic extension. In this catenotaeniid, the proximal fusion is preceded by a 90° rotation of the flagellum. The spermatozoon is a Levron et al. type VI, which presents a single axoneme with the 9 + '1' trepaxonematan pattern, a periaxonemal sheath, two crest-like bodies, twisted cortical microtubules, and a spiraled nucleus. The obtained results show similarities with the remaining studied catenotaeniids, namely Catenotaenia pusilla and Skrjabinotaenia lobata. The results are compared and discussed according to several characteristics found in the catenotaeniids and other studied cyclophyllideans.

Echinococcus multilocularis Leuckart, 1863 (Taeniidae): new data on sperm ultrastructure

The present study establishes the ultrastructural organisation of the mature spermatozoon of Echinococcus multilocularis, which is essential for future research on the location of specific proteins involved in the sperm development in this species and also in Echinococcus granulosus. Thus, the ultrastructural characteristics of the sperm cell are described by means of transmission electron microscopy. The spermatozoon of E. multilocularis is a filiform cell, which is tapered at both extremities and lacks mitochondria. It exhibits all the characteristics of type VII spermatozoon of tapeworms, namely a single axoneme, crested bodies, spiralled cortical microtubules and nucleus, a periaxonemal sheath and intracytoplasmic walls. Other characteristics observed in the male gamete are the presence of a >900-nm long apical cone in its anterior extremity and only the axoneme in its posterior extremity. The ultrastructural characters of the spermatozoon of E. multilocularis are compared with those of other cestodes studied to date, with particular emphasis on representatives of the genus Taenia. The most interesting finding concerns the presence of two helical crested bodies in E. multilocularis while in the studied species of Taenia, there is only one crested body. Future ultrastructural studies of other species of the genus Echinococcus would be of particular interest in order to confirm whether or not the presence of two crested bodies is a characteristic of this genus.