LOCALIZATION OF ESTROGEN-RECEPTORS IN LONG BONES AND VERTEBRAE OF HUMAN FETUSES

In order to investigate the possible role of estrogen in the developme nt of cartilage and bone we studied by immunofluorescence immunohistoc hemistry and autoradiography 26 human embryos and fetuses 7-22 weeks i n gestational age associated with pregnancy interrupted for nonmedical reasons. In order to demonstrate the presence of estrogen receptors ( ERs) in human fetal cartilage, cryostat sections of long bones and lum bar and thoracic vertebrae were prepared for (1) fluorescent immunocyt ochemistry using an antiidiotypic monoclonal antibody to antiestradiol receptor monoclonal Ab labeled with fluorescein isothiocyanate (FITC) , (2) immunohistochemistry using monoclonal antihuman estradiol recept or antibody, labeled with strept. A-B immunoperoxidose, and (3) autora diographic localization of estradiol using labeled (H-3) 17beta estrad iol. In fetuses aged 10 weeks or older, intranuclear and perinuclear l ocalization of ER was demonstrated by all methods, mainly amongst chon drocytes of the proliferating and higher hypertrophic zones of the epi physes and in the cartilage of vertebral bodies. These data suggest th at estrogen acts directly on chondrocytes of human fetuses through an ER-mediated mechanism.