Localization of androgen receptors in ram epididymal principal cells

Androgen receptor was immunolocalized in the epididymal epithelium of rams and in isolated cells using an antibody against a synthetic polypeptide representing a portion of the androgen receptor. Immunostaining was predominant in the epithelium in tissue sections. Concentrations of androgen receptor were determined in cells from the central caput, distal caput, and central corpus epididymidis enzymically dissociated and elutriated to provide two fractions. On the average (n = 18), Fraction I contained 8% principal cells while Fraction II contained 71% principal cells; the stromal cells in each fraction were primarily smooth muscle and fibroblasts. For each sample, the number of DHT receptors (fmol) per 10(6) total cells was greater in Fraction II than in Fraction I. Few cells in Fraction I were immunostained for androgen receptor, whereas most cells in Fraction II were intensely stained. The numbers of DHT receptors per cell, or per principal cell, were similar for the central caput and distal caput, but lower in the central corpus epididymidis. The results support our hypothesis that most epididymal DHT receptors are localized in principal cells and confirm that the region between the central caput and proximal corpus of the ram epididymis is most dependent on androgen stimulation.