We examined the immunolocalization of estrogen receptor (ER)α and ERβ in the human fetal prostate.

Tissue sections from human fetal prostates at 7 to 22 weeks of gestation were stained with antibodies to ERα, ERβ, and cytokeratin 10 and 14.

ERα expression was not detected until 15 weeks of gestation with sparse staining in the utricle. By 19 weeks increased ERα 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 ERα expression was more intense in all of these areas. ERβ was expressed throughout the UGE, ejaculatory ducts, müllerian ducts and entire stroma at 7 weeks. Intense ERβ staining was observed in these areas and in the prostatic buds by 8 weeks with persistent intense staining through 22 weeks.

To our knowledge we report the first immunolocalization of ERα in the human fetal prostate and the earliest demonstration of ERβ expression in the prostate at 7 weeks of gestation. ERβ 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 ERα expression in these areas, while the induction of squamous metaplasia in peripheral prostatic acini is associated with peripheral stromal ERα expression. This study suggests estrogen signaling pathways in the human fetal prostate via ERα that involve epithelial-epithelial and epithelial-stromal interactions.