ESTROGEN-RECEPTORS ARE PRESENT IN THE EPIDIDYMIS OF THE ROOSTER

Our recent discovery that testicular germ cells and epididymal sperm c ontain active P450 aromatase suggests that the reproductive tract may be a target for estrogen. Therefore, the objective of this study was t o determine if estrogen receptors (ER) are present in the avian epidid ymis using immunocytochemistry, northern blot analysis, and in situ hy bridization. Immunoperoxidase staining for ER was found principally in nuclei of nonciliated epithelial cells of proximal and distal efferen t ductules and the epididymis duct. The ciliated cells also appeared t o be slightly positive in the efferent ductules. Weak immunostaining w as also observed in the connective tissue of the epididymis duct. Immu nostaining was more intense in epithelial cells of the efferent ductul es than in epithelial cells of the epididymal duct or connective tissu e cells. Strong specific hybridization signals for ER mRNA corresponde d to the same areas exhibiting immunocytochemical localization. The pr esence of ER mRNA in the epididymis was confirmed by northern blot ana lysis, which showed a single band corresponding to approximately 7.8 k b, similar to that found in chicken oviduct. Based on these data, we s uggest that the efferent ducts of the rooster are a primary target for estrogen and that estrogen may have a role in the regulation of avian epididymal function.