Age-, Cell- and Region-Specific Immunoexpression of Estrogen Receptor (But Not Estrogen Receptor ) during Postnatal Development of the Epididymis and Vas Deferens of the Rat and Disruption of This Pattern by Neonatal Treatment with Diethylstilbestrol

This study in rats sought to 1) characterize immunoexpression of estrogen receptor α (ERα) and ERβ in the efferent ducts, epididymis, and vas deferens during postnatal development; 2) establish whether ER expression changed after neonatal treatment with diethylstilbestrol (DES); and 3) determine whether ER changes coincided with abnormal epididymal/vas development. Rats were administered 10μ g DES or vehicle on days 2, 4, 6, 8, 10, and 12 and were sampled on days 10, 18, 25, 35, and 90+. At all ages, ERα was immunoexpressed intensely in the efferent ducts. On day 10, immunoexpression of ERα was absent from the epididymis and vas, but was detectable on day 18 in epithelial cells in the caput, corpus, and proximal cauda. Epithelial expression of ERα was absent from the distal cauda and in the proximal and distal vas was confined to a band of periductal stromal cells. Thus, on day 18, the site of ERα expression delineated the epididymis-vas boundary. On days 25–35, epithelial expression of ERα was absent, but stromal expression persisted in the vas and distal cauda. In adults, immunoexpression of ERα in the epididymis and vas was absent. In contrast, ERβ was immunoexpressed in epithelial cells and some stromal cells in the efferent ducts, epididymis, and vas at all ages. In the vas, stromal expression of ERα and ERβ was in different layers. DES treatment caused 1) underdevelopment of the epididymal duct and reduced epithelial height in epididymis and vas; 2) coiling of the extraepididymal vas; 3) thickening of the periductal actin-free stromal layer in the distal cauda and vas; and 4) reduced cell proliferation on day 18 in the epididymis and vas, based on incorporation of bromodeoxyuridine, especially in the epithelium. These changes coincided with abnormalities in cell- and region-specific immunoexpression of ERα, but not ERβ. Thus, in DES-treated rats on day 18, epithelial expression of ERα occurred in all regions of the epididymis and vas instead of being confined to the caput, corpus, and proximal cauda as in controls. Similarly, stromal ERα expression in the vas of DES-treated rats was not confined to a periductal layer as in controls, but occurred diffusely in the muscle layer. It is suggested that 1) estrogens play a role in peripubertal development of the epididymis and vas; 2) the cellular site of expression of ERα either plays a role in or reflects demarcation of the epididymal/vas boundary; and 3) blurring of this boundary in DES-treated rats coincides with altered ERα immunoexpression.