Effects of estradiol and promegestone on human breast cell cultures. An ultrastructural study

Effects of estradiol (E2) and promegestone (R 5020) were tested on primary cultures of epithelial human breast cells prepared from surgical specimens of reduction mammoplasty. Comparative morphological studies were performed by means of transmission and scanning electron microscopy in cells without any hormonal adjunction and in those previously treated with E2 or E2 + R 5020. The results were as follows: In basal medium used as control the majority of epithelial cells, although well-differentiated, remained flat with few microvilli, well-developed Golgi apparatus and rough endoplasmic reticulum, was obvious. R 5020 added with E2 increased differentiation of epithelial cells covered with scarce long and branched microvilli, but reduced the turn-over of young cells. E2 seemed to generate more active proliferation of cells. R 5020 inhibited this effect and induced a higher differentiation of mammary epithelial cells.