Transepithelial movement of 3H-androgen in seminiferous and epididymal tubules: a study using in vivo micropuncture and in vivo microperifusion.

In vivo micropuncture and a new system of in vivo microperifusion were used to examine the movement of 3H-androgen from blood to lumen and from interstitum to lumen in the rat testis and epididymis. Movement of 3H-androgen into the seminiferous tubule lumen was restricted, with intraluminal isotope concentrations plateauing at approximately 15% of extratubular isotope concentrations whether the 3H-androgen originated in the vascular or interstitial compartments. In the caput epididymidis, intraluminal 3H-androgen plateaued at approximately 35% of serum concentrations, but when 3H-androgens were presented directed to the basal aspect of the caput epididymidal epithelium, 3H-androgen was transported into the lumen against a concentration gradient. Intraluminal isotope concentrations were greater than 200% of those in the epididymal interstitial compartment. Similar results were found for the cauda epididymids. Factors controlling the proluminal movement of 3H-androgens in the rat testis and epididymis were therefore fundamentally different.