Immunohistochemical localization of estrogen‐specific 17β‐hydroxysteroid oxidoreductase in the human and mouse prostate

The estrogen-specific 17β-hydroxysteroid oxidoreductase (17β-HSOR) enzyme protein was stained immunohistochemically in the newborn and adult human prostate as well as in the mouse prostate. In the newborn human prostate, ductal and urethral epithelia were faintly stained, whereas in the adult human prostate, intense staining for 17β-HSOR enzyme antigen could be detected in the epithelium of the collecting ducts and urethral epithelium as well as in the epithelium of the intraprostatic vas deferens and seminal vesicle epithelium. Immunostaining was weak in the prostatic tissues of both newborn and adult prostate. No positive cells were found in stroma. The activity of NADPH-dependent 3H-estrone reductase was detectable in cell-free homogenates prepared from human prostatic tissues. The activities showed a good correlation with immunocytochemical findings. In the mouse, neonatal estrogenization resulted in intensively stained epithelium of the collecting ducts at the age of 14 days. Moreover, when adult control and neonatally estrogenized mice were implanted with 17β-estradiol, the metaplastic epithelium of the periurethral collecting ducts of neonatally estrogenized mice was intensively stained with 17β-HSOR. These findings suggest that metaplastic epithelium rises from 17β-HSOR-positive cells. The similar distributions of 17β-HSOR-positive cells confirm the concept of homology in the posterior estrogen-responsive periurethral region (containing the periurethral ducts and periurethral glands) of the mouse and humans. Our findings further suggest that the 17β-HSOR-positive cells may have the same origin and hormonal control in both species. © 1994 Wiley-Liss, Inc.