Localization of estrogen receptors in long bones and vertebrae of human fetuses.

In order to investigate the possible role of estrogen in the development of cartilage and bone we studied by immunofluorescence immunohistochemistry and autoradiography 26 human embryos and fetuses 7-22 weeks in gestational age associated with pregnancy interrupted for non-medical reasons. In order to demonstrate the presence of estrogen receptors (ERs) in human fetal cartilage, cryostat sections of long bones and lumbar and thoracic vertebrae were prepared for (1) fluorescent immunocytochemistry using an antiidiotypic monoclonal antibody to anti-estradiol receptor monoclonal Ab labeled with fluorescein isothiocyanate (FITC), (2) immunohistochemistry using monoclonal antihuman estradiol receptor antibody, labeled with strept. A-B immunoperoxidase, and (3) autoradiographic localization of estradiol using labeled (3H) 17 beta estradiol. In fetuses aged 10 weeks or older, intranuclear and perinuclear localization of ER was demonstrated by all methods, mainly amongst chondrocytes of the proliferating and higher hypertrophic zones of the epiphyses and in the cartilage of vertebral bodies. These data suggest that estrogen acts directly on chondrocytes of human fetuses through an ER-mediated mechanism.