Ontogeny of TR?1 expression in the mouse testis and epididymis during postnatal development

Abstract

Thyroid hormone (T3) acts on the testis via thyroid hormone receptor alpha 1 (TR?1), though the cellular localization of TR?1 in testis remains controversial. Studies on the presence of TR?1 in the epididymis are also lacking. The present study, therefore, examined the cellular localization and expression pattern of TR?1 in testis and epididymis of Parkes mice during postnatal development. Immunohistochemical results showed localization of TR?1 in interstitial and tubular compartments of the testis all through the development. On postnatal day (PND) 14, only leptotene spermatocytes showed TR?1-immunoreactivity in the testis, while at PND 28, 42, and 90, a diverse staining pattern for TR?1 was seen in almost all the seminiferous tubules mainly in leptotene spermatocytes, round and elongating spermatids, and in Leydig cells. Further, qRT-PCR and immunoblot analyses showed that TR?1 was expressed in the testis at the transcript as well as protein level throughout the postnatal development. TR?1 was also seen in principal cells of the epididymis, with maximal expression at PND 90. TR?1 was also present in cauda epididymidal spermatozoa of adult mice at PND 90. The results suggest that TR?1 is expressed in the testis and epididymis and that it may help to regulate the spermatogenic process and male fertility. � 2022 Wiley-VCH GmbH.