Printed in U.S.A. Copyright © 1998 by The Endocrine Society Transcription and Translation of Estrogen Receptor- � in the Male Reproductive Tract of Estrogen Receptor-� Knock-Out and Wild-Type Mice*

Estrogen receptor-α (ERα) has been identified in the male reproductive tract, but the role of estrogen in the male has not been well characterized. In vivo mutations in ERα genes have demonstrated the necessity for ERα-mediated action in male fertility. We asked whether both ERβ messenger RNA and protein were present in the male reproductive tract of wild-type and ERα knock-out (ERα KO) mice, and whether ERβ could compensate for the lack of ERα in infertile male ERα KO mice. Immunohistochemical localization with both N- and C-terminal anti-ERβ antibodies demonstrated that ERβ is present in the Leydig cells of the testes and in the epithelium of both the efferent ductules and the initial segment of the epididymis. RT-PCR amplification was used to confirm ERβ transcription in these tissues. In conclusion, we observed that ERβ messenger RNA and protein continue to be expressed in the Leydig cells, elongated spermatids, efferent ductules, and the initial segment of the epididymides of ERα KO mice, but the pre...