Immunolocalization of estrogen receptor α and β in human fetal prostate

Purpose: We examined the immunolocalization of estrogen receptor (ER)a and ER beta in the human fetal prostate. Materials and Methods: Tissue sections from human fetal prostates at 7 to 22 weeks of gestation were stained with antibodies to ER alpha, ER beta, and cytokeratin 10 and 14. Results: ER alpha expression was not detected until 15 weeks of gestation with sparse staining in the utricle. By 19 weeks increased ER alpha expression was seen in the luminal cells of the ventral urogenital epithelium (UGE), basal cells of the dorsal UGE, utricle, distal periurethral ducts, peripheral stroma and posterior prostatic duct. K14 was detected in basal cells of the UGE and in several posterior acini. At 22 weeks ER alpha expression was more intense in all of these areas. ER beta was expressed throughout the UGE, ejaculatory ducts, mullerian ducts and entire stroma at 7 weeks. Intense ER beta staining was observed in these areas and in the prostatic buds by 8 weeks with persistent intense staining through 22 weeks. Conclusions: To our knowledge we report the first immunolocalization of ER alpha in the human fetal prostate and the earliest demonstration of ER beta expression in the prostate at 7 weeks of gestation. ER beta expression is intense during ductal morphogenesis, suggesting a role in normal glandular growth and proliferation. The induction of squamous metaplasia in the UGE, distal periurethral ducts and utricle is associated with ER alpha expression in these areas, while the induction of squamous metaplasia in peripheral prostatic acini is associated with peripheral stromal ER alpha expression. This study suggests estrogen signaling pathways in the human fetal prostate via ER alpha that involve epithelial-epithelial and epithelial-stromal interactions.