Estrogen Receptor in the Ductuli Efferentes, Epididymis, and Testis of Rhesus and Cynomolgus Macaques1

We obtained the testes, ductuli efferentes, and epididymides from adult rhesus and cynomolgus macaques and examined these tissues for estrogen receptors (ER) with immunocytochemistry (ICC) and a sucrose gradient assay. Both techniques employed monoclonal antibodies prepared against ER, and both showed that high concentrations of ER were present OFFy in the ductuli efferentes. Moreover, all specific staining was confined to the nuclei of the nonciliated, absorptive epithelial cells. The quantity of salt-extractable ER in the ductuli efferentes (834 +/- 161 [SEM] fmol/mg DNA [n = 8]) did not differ significantly from the amounts measured with the identical assay in oviducts and endometrium of estrogenized female macaques. Testes and epididymides of macaques had no specific staining by ICC and barely detectable amounts by biochemical analysis (7 +/- 4 [n = 3], 8 +/- 2 [n = 5], 33 +/- 16 [n = 3], and 6 +/- 3 [n = 8] fmol/mg DNA for testis and caput, corpus, and cauda epididymis, respectively). The functional significance of the high levels of ER in the ductuli efferentes of macaques remains to be determined.