Ultrastructure of human endometrial epithelium in monolayer culture with and without steroid hormones.

Colonies of cells of epithelioid appearance were identified in monolayer cultures grown up to 50 days from normal human endometrial cell suspension obtained by a method designed to insure a maximum harvest of glandular cells. Groups of these cells were separated from stromal cells by means of cloning cylinders. Studies comparing the ultrastructure of cells of this type to fresh endometrial tissue revealed a number of similarities. The morphological characteristics common to both types of samples included junctional complexes, perinuclear microfilaments and microvilli with glycocalyx. Other common features were prominent nucleoli, well developed Golgi, rough endoplasmic reticulum and membrane-bound electron-dense bodies in the cytoplasm. A stripping technique applied to the fetal bovine serum used in the nutrient medium made it possible to initiate cultures in a steroid-free environment and to maintain them in the presence of the specified concentration of estradiol and/or progesterone. Isolation of epithelial cells of endometrium in monolayer culture may provide a useful model system in which to study the specific effects of steroid hormones on cellular function and differentiation.