[Analysis of the abortive action induced by prostaglandin F2 alpha in the mouse. Study of ova and their transplantation].

In mice PGF2 alpha injections (120 mg/kg from first to the 4th day) determines a high proportion of early abortions. The mechanism of this action has been investigated by transplantation of blastocysts removed from PGF2 alpha treated mice to pseudopregnant mice. The results of transplantation experiments indicate that the percentage of implantation is the same whether the eggs are taken from PFG2alpha treated or control mice. The number of eggs present in the uterine horns 84 hours after fertilization is 40 % lower than in control animals. At an earlier stage, 60 hours after fertilization, the uterus of PGF2 alpha treated females contains 85 % of eggs as compared to 20 % in controls. This proportion is reversed in the fallopian tubes. It can therefore be concluded that the high abortion rate of PGF 2 alpha treated mice is not due to an embryotoxic effect but to a faster transport of the fertilized eggs which reach therefore the uterus before implantation can take place.