The structure of the epididymis of the giant rat (Cricetomys gambianus, Waterhouse): histological, histochemical and microstereological studies.

The structure of the ductus epididymidis of the African giant rat (Cricetomys gambianus, Waterhouse) was studied by means of histological (paraffin and plastic-embedded tissues) and histochemical techniques. Five distinct zones (I-V) were detected along the epididymal duct on the basis of epithelial height and cytological composition and structure. The so-called apical cells, which have been observed in some species of animals, were not seen in the initial segment of the duct. Clear or light cells were present in the epithelium of the terminal segment, thus making the giant rat the third species in which this cell has been found, after the laboratory rat and the hamster. A large number of intra-epithelial lymphocytes and macrophage-like cells was commonly observed in the epithelium throughout the duct; the latter were strongly PAS-positive while the former tended to increase in number caudally. A microstereological study of the epididymis showed that Zones I (initial segment) and II contained a significantly (P less than 0.001) higher proportion of epithelium and a relatively greater (P less than 0.001) proportion of blood vessels in the interductal connective tissue than the more caudal segments of the epididymis which possessed a significantly (P less than 0.01) higher proportion of interductal connective tissue.