Effect of RMI 12,936 on early pregnancy in mice

Treatment with RMI 12,936 blocked the mitotic shift from epithelial to stromal cells normally observed in the uterus on Day 4 of pregnancy, and inhibited implantation. While progesterone alone could reverse the change in pattern of cell division in the preparation of the uterus for implantation, both oestradiol and progesterone were necessary to induce implantation and maintain pregnancy. A reduction in the activity of delta 5-3 beta-hydroxysteroid dehydrogenase in the ovaries of RMI 12,936-treated mice suggests that the compound affects luteal synthesis of oestrogen and progesterone in mice.