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SUMMARYThe reproductive duct of the male blood fluke Schistosoma mansoni is relatively short and undulating, extending from the most posterior testis to the beginning of the gynecophoric canal. The reproductive duct may be divided into 3 main regions which differ in ultrastructure; the vas efferens/deferens, the seminal vesicle and the cirrus tube. The epithelium of the vas efferens/deferens consists of a single layer of elongate cells with abundant convoluted lamellae on their apical surfaces. The wall of the seminal vesicle and the cirrus tube are tegumentary in nature. The basic similarities in structure of the surface tegument, the seminal vesicle and the cirrus tube suggest a common embryological origin. The presence of complex lamellae on the luminal surface suggests that the vas efferens and deferens have secretory and possibly nutritive functions apart from temporarily storing developing germ cells. The primary function of the seminal vesicle appears to be that of sperm storage; while the cirrus tube with its complex infolded wall is extensible for insemination. The presence of abundant concentrically distributed sensory papillae around the male genital pore may assist in the pairing of males and females.

SUMMARYStudies on the multiple compact testes of Schistosoma mansoni have revealed 2 principal cell types: germinal and non-germinal cells. Two morphological forms representing different stages in the cytomorphosis of the sustentacular cells have been considered. The polymorphic sustentacular cells which are conspicuously stained with potassium permanganate contain abundant ribosomal endoplasmic reticulum, glycogen particles and ribosomal masses in comparison with the germinal component of the testes. Golgi complexes with associated secretory bodies and vacuoles are present in the cells. The cytoplasm of the sustentacular cells interdigitate between other cells in the testes. Based on their morphology, nutritive, supportive and phagocytic functions have been attributed to the sustentacular cells. The possible recycling of nutrients by the cells is discussed. It is suggested that the cells regulate the production of spermatozoa from a nutritive viewpoint and also that the translocation of nutrients from the parenchyma to the testes is facilitated by these cells whose cytoplasm extends directly adjacent to the basal lamina.