Immunolocalization of receptors for androgen and estrogen in male caprine reproductive tissues: Unique distribution of estrogen receptors in efferent ductule epithelium

Androgens and estrogens affect physiological processes in the testis and male excurrent duct system. This study was designed to identify and characterize distribution of androgen receptors (AR) and estrogen receptors (ER) in the reproductive organs of the male goat. Tissues, including testis, efferent ductules, epididymis (regions I-V), and ductus deferens, were obtained from five mature Nubian goats, fixed in 4% paraformaldehyde, and embedded in paraplast. Antigenic sites for AR were unmasked by microwave treatment (four times, 5 min each) of tissue sections immersed in 10 mM citrate (pH 6) and were detected using the PG-21 rabbit anti-rat/human antibody. Antigenic sites for ER were identified using the H-222 rat anti-human monoclonal antibody after tissue sections were treated with pronase (0.5 mg/ml, 37 degrees C, 8 min). Avidin-biotin horseradish peroxidase procedures were used to identify positive immunoreactivity, irrelevant IgG was substituted for primary antibody in negative controls. Positive nuclear immunostaining for AR was observed in all types of epithelial cells, peritubular smooth muscle cells, and intertubular fibroblasts of the intratesticular rete, efferent ductules, epididymis (regions I-V), and ductus deferens, as well as in Sertoli, Leydig, and peritubular myoid cells and intertubular fibroblasts of the testis. In contrast, nuclear immunostaining for ER was confined to nonciliated cells of the efferent ductules. Thus, AR-positive cells are ubiquitously distributed in caprine testicular and excurrent ductular tissues, and ER-positive cells are unique to the efferent ductules. The caprine model should be useful in studies designed to determine mechanisms through which androgens and estrogens regulate development and function of the testes and excurrent ducts.