No abstract

To determine whether estrogen and prostaglandins have a direct effect on the preimplantation embryo, the effect of these compounds added to mouse embryos in vitro was examined. Embryos were incubated in culture media containing [3H]uridine with or without the substances to be tested. The addition of estradiol (10(-8)M) and prostaglandin F2 alpha (1 microgram/ml or 10 micrograms/ml) stimulated the incorporation of uridine into RNA. However, prostaglandin E2 at a concentration of 10 micrograms/ml had an inhibitory effect. These findings indicate that estradiol and prostaglandin F2 alpha may have, in addition to an indirect effect mediated by uterine factors, a direct effect on embryonic growth that activates embryos to implant.