Abstract
The administration of estrone in peanut oil, and estradiol benzoate in sesame oil in dosages of .2 mg daily to pregnant Webster-Swiss-strain-mice from the 11 through 16 days of gestation produced approximately 13% cleft palates in the large number comprising each group. Estrone, however, produced a markedly greater number of absorbed fetuses, the ratio of absorbed fetuses to intact fetuses being 85% for estrone and 36% for estradiol. Additional data was adduced which suggested that if estrogen were maintained at a plateau level, the fetuses are apt to be absorbed rather than coming to term with cleft palates. The overall evidence demonstrates that parenteral estrogen has teratogenic effects on developing mice embryos.