Binding of estrogen and progesterone to human endometrium in the different phases of the menstrual cycle. A histochemical study.

Specific estrogen and progesterone binding in human endometrium was studied histochemically using fluorochrome-labeled steroids (estradiol-17 beta-BSA-FITC and progesterone-BSA-TMRITC), endometrial samples from 36 women being investigated. The binding pattern was similar with both reagents. The relationship between the bindings to glands and to stroma, however, varied with the menstrual phase of the tissue. The specific fluorescence was more intense in the epithelial structures in the proliferative phase. In the secretory phase, the fluorescence from stromal cells was as intense as, or more intense than, that from the glands. The localization of the fluorophores in the glandular epithelial cells also varied by menstrual phase. In the proliferative phase, the fluorescence was most intense in the basal part or the whole cytoplasm of the glandular epithelial cells, while in the secretory phase the fluorescence was most intense in the apical and sometimes also in the basal part of the epithelial cells.