Embryotoxic effects of post-coital fertility inhibiting steroids.
In mice post-coital estrogens caused retardation of tubal egg cleavage, whereas post-coital progestins stimulated egg division. In rats the situation was reversed. In this species estrogens accelerated the tubal embryo development and vice versa; the progestin STS 557 arrested division of embryos resting in the tube. Normal implantation occured following transfer of early blastocysts from estrogen-treated mice to untreated mice, but not following transfer of blastocysts from untreated animals to estrogen-treated animals. This shows that post-coital estrogens do not affect the embryos directly but they disturb the physiological integrity of the endometrium required for proper implantation.
D000014:Abnormalities, Drug-Induced / Q000473:pathology; D000818:Animals; D001755:Blastocyst / Q000187:drug effects; D003281:Contraceptives, Postcoital / Q000633:toxicity*; D003282:Contraceptives, Postcoital, Hormonal / Q000633:toxicity*; D004622:Embryo, Mammalian / Q000187:drug effects*; D005187:Fallopian Tubes / Q000502:physiology; D005260:Female; D051379:Mice; D011247:Pregnancy; D051381:Rats
D003281:Contraceptives, Postcoital; D003282:Contraceptives, Postcoital, Hormonal