Contraceptive action of intra-uterine devices in the ferret.

To study the effect of an intra-uterine device on conception in the ferret silk suture IUDs were inserted into either the left or right uterine horns of female ferrets who were mated 2 weeks later at the height of estrus. 15 ovaries examined at autopsy after mating found no difference in the number of eggs shed by the IUD and control ovaries. Fertilization in both IUD and control ferrets 72 hours after mating was normal. Egg transport and embryonic development 168 hours after mating appeared normal in both IUD and control animals but after 240 hours embryo recovery was much lower in the IUD animals than the controls and the blastocysts examined were degenerate. The IUDs effect on conception in the ferret is variable and incomplete but does not depend on disturbing the hormonal background to pregnancy which remained normal in the IUD-treated animals. The IUD in the ferret seems to exert its greatest effect on the pre-implanation phase of conception.