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

Abstract

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.

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

“…Thus, sperm cells with two axonemes are present in the orders Diphyllobothriidea, Spathebothriidea, Haplobothriidea, Onchoproteocephalidea, and Trypanorhyncha [21][22][23][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60]. Contrarily, spermatozoa with one axoneme are present in the orders Caryophyllidea, Cyclophyllidea, Lecanicephalidea, Nippotaeniidea, Phyllobothriidea, and Tetrabothiidea [21][22][23][26][27][28][29][30][31][32][61][62][63][64][65][66][67][68][69][70][71][72]. In the order Diphyllidea, there are some discrepancies between the spermiogenesis process and the resulting spermatozoa.…”

“…In the Cestoda, there are numerous ultrastructural studies describing spermiogenesis and/or the spermatozoon, particularly in the order Cyclophyllidea [ 23 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. However, in the Catenotaeniidae family, ultrastructural aspects of spermiogenesis and/or the spermatozoon have only been studied in two species, namely Catenotaenia pusilla (Goeze, 1782) (Catenotaeniinae Spassky, 1950) and Skrjabinotaenia lobata (Baer, 1925) (Skrjabinotaeniinae) [ 33 , 34 ].…”