Morphological evidence for a blood-epididymis barrier and the effects of gossypol on its integrity.

Ultrastructural and micropuncture techniques were used to obtain morphological evidence for a blood-epididymis barrier ( BEB ) in the rat and to determine whether gossypol, an oral male contraceptive, alters the permeability of the BEB or blood-testis barrier ( BTB ) in rats made infertile with gossypol. Rats were treated by gavage with 20 mg/kg per day of gossypol for 6 weeks; control animals received the vehicle alone. For electron microscopy the components of the BEB were analyzed in each region of the epididymis with intravascularly perfused lanthanum nitrate. Throughout the epididymis in both control and gossypol-treated animals it was found that the zonula occludens at the apicolateral surface of the epididymal epithelial cells was the sole and ultimate structural component of the rat BEB ; the flow of intravascularly perfused lanthanum was not significantly impeded by the vascular endothelium, the peritubular myoid layer or other lateral cell surface specializations. For micropuncture, control and treated rats were administered 0.3 mCi [3H]inulin via the jugular vein. Radioactivity was determined in samples collected from the seminiferous tubules, caput and cauda epididymidis, and carotid artery. Results showed that [3H]inulin entry in seminiferous tubules, caput and caudal luminal fluid from blood was similar for control and treated groups. It was concluded that gossypol treatment does not alter the permeability properties of the BTB and BEB to macromolecules such as inulin or to small electron-dense tracers such as lanthanum.