EFFECTS OF UTERINE DISTENSION AND OESTRADIOL ON CELL KINETICS IN THE ENDOMETRIAL EPITHELIUM OF OVARIECTOMIZED RATS

Abstract

Cell kinetics in the uterine epithelium of ovariectomized rats were studied after uterine distension and/or an estradiol injection, by cumulative 3H-TdR [3H-thymidine] labeling and percentage of labeled mitoses (PLM). Both methods showed that distension shortens the total cell cycle at the expense of G1 more than does estradiol. Both treatment act in a cumulative manner since the greatest reduction in Tc [cell cycle time] is observed after distension plus estradiol. PLM curves showed that distension and/or estradiol induce a 30% reduction in S phase duration. The evolution of percentages of labeled cells and colchicine-blocked mitoses after these treatments confirmed their additive effects and indicated that the mitogenic action of estradiol was delayed compared to that of distension. These factors probably stimulate epithelial cell division in the uterus through partly different metabolic channels.