[Nidation in the Triton W.R. 1339 treated mouse: effect of progesterone and estradiol]

In the mouse injection of 800 mg/kg of Triton W.R. 1339 during the first four days of gestation prevents nidation. Examination of the uterine horns between days 6-12 reveals that a daily injection of 5 mg progesterone up from day 1 of gestation assures the survival of the blastocysts in Triton W.R. 1339 treated females and determines a delayed nidation. Nidations occur only after injection of 0.1 microgram of oestradiol benzoate at the beginning of the 5th day.