Estrogen receptors in epithelial and stromal cells of human endometrium in culture

Abstract

Estradiol (E 2) receptor concentrations were measured in endometrial tissue, in isolated glands, in stromal cell preparations and in monolayer cultures derived from these fractions. The levels of E 2 receptors (ER) tended to be higher in stroma than in glands. The decline of ER levels occurring in whole tissue during the luteal phase of the menstrual cycle was also observed in both glands and stroma. Throughout the menstrual cycle, a significant fraction (25–70%) of the total ER was found as available receptors, i.e. not bound to E 2, in nuclei from either whole tissue or the separated components. Levels of estrogen receptors were measured daily in glandular epithelial and stromal cells during the first week in culture. An initial disappearance of ER was followed by an increase in ER to levels higher than those present in the original preparations and by a subsequent decline to negligible values. Subcultures showed low ER levels which then increased. Addition of E 2 to the medium elevated these levels and addition of medroxyprogesterone acetate (MPA) reduced them. Relatively low levels of available nuclear receptors were found in cells in culture.