Anionic sites in the basement membrane of the rat epididymal epithelium during ontogenesis and after testicular and gonadal tract lesions.

Anionic binding sites in the lamina densa of the basement membrane of the rat epididymal epithelium were demonstrated ultrastructurally with the use of cationized polyethyleneimine (PEI). Enzyme digestion with heparitinase removed the anionic sites, indicating that they consist largely of heparan sulfates. The anionic sites are present as early as the 16th day of gestation on the interstitial face of the lamina densa; later during gestation they are localized on both faces of the lamina densa without further modification after birth. The distribution of the anionic sites was identical all along the epididymal duct. After castration and ligation of efferent ducts or in the state of cryptorchidism the sites were more numerous and located inside the thicker portion of the lamina densa. These alterations were more prominent in the initial segment compared to the distal segments, suggesting a differential androgen dependence of the reactive sites and their patterns of distribution.