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Abstract
The process of Spermatogenesas in Sandonia sudanensis and Basidiodiscus ectorchis studied by light and transmission electron microscopes. Spermatogenesis begins with spermatogonia occupying the periphery of the testis. They undergo a series of mitotic and meiotac divisions resulting in the formation of clusters of 32 spermatids that develop into 32 spermatozoa.
Spermiogenesis is marked by the formation of the zone of differentiation containing 2 basal bodies growing perpendicular to the microtubule organizing centre (MTOC). The differentiating zone extends away from the spermatid cell forming the median cytoplasmic process. Two axonemes develop from the basal bodies then they rotate through 90° and extend parallel to the median process, and finally fuse with the latter spermatozoon. to form the
The mature spermatozoon possesses 2 axonemes of the 9+ ”1” pattern typical of parasitic Platyhelminthes. The value of sperm ultrastructure as a taxonomic tool in phylogeny is discussed.
The general body surface of both paramphistomes is aspinose with the tegument comprising an outer anucleate surface syncytium underlain by a thick subsyncytial zone and musculature. The nucleated tegumental cells, of single type are deeply situated and produce both t1 and t2 inclusion bodies that are transported.