Androgen receptor and 5α-reductase activity in the ductuli efferentes and epididymis of adult rhesus macaques

We measured androgen receptors (AR) and 5α-reductase activity (5αRA) in the ductuli efferentes and epididymides from adult rhesus macaques. Tissue samples were either assayed biochemically for AR or stained immunocytochemically (ICC) with a monoclonal antibody against AR. To estimate 5αRA, tissue microsomes were incubated with [1α,2α-³H]testosterone, and the [³H]dihydrotestosterone formed was quantified. We found significant regional differences in the levels of both 5αRA and AR in the excurrent ducts. In general, both enzyme activity and AR levels were higher in the caput and corpus epididymis than in ductuli efferentes and cauda epididymis. With ICC, positive nuclear AR staining was detected in all epithelial cell types, whereas variable numbers of stromal cells were positively stained. Our data demonstrate that there are segmental differences in the concentrations of 5αRA and AR in epididymis and suggest that there may be regional differences in the regulation of epididymal functions by androgen.