Nuclear estrogen binding sites in human endometriosis

With a technique of in vitro steroid autoradiography, the localization of nuclear estrogen binding sites has been studied in ovarian endometriotic foci from untreated patients in both the follicular and luteal phases of the cycle. Unlike the uterine endometrium, which displays cyclic changes in estrogen binding sites, the endometriotic foci show no such changes in the localization of estrogen binding sites. Throughout the cycle, a marked degree of estrogen binding is present in the stromal cells of the endometriotic foci, while in the uterine endometrium stromal binding sites are seen only during the proliferative phase and not during the secretory phase of the cycle. The glandular epithelium of the endometriotic foci displays a patchy localization of nuclear estrogen binding sites at all stages, while the glandular epithelium of the uterus is strongly positive during the proliferative phase but displays no estrogen binding sites during the secretory phase of the cycle. Thus, the endometriotic foci appear to respond differently to ovarian hormones, both in terms of the modulation of estrogen binding and in terms of glandular histology.