TREATMENT WITH GONADOTROPINS IMPAIRED IMPLANTATION AND FETAL DEVELOPMENT IN MICE

Purpose: The effect of gonadotropins on implantation and fetal develop ment in mice was investigated by superovulation with pregnant mare ser um gonadotropin and human chorionic gonadotropin. In a previous study fetal growth was found to be highly retarded. Results: Assessment of i mplantation in vivo revealed that late implantation did occur. Gestati onal length was highly extended, the mean number of live fetuses per p regnant mouse was lower and their mean weight significantly reduced. I n vitro experiments revealed no significant difference in the rate of blastocyst adhesion and trophoblast outgrowth development. Immunohisto chemical staining, however, showed that blastocysts from superovulated mice had smaller trophoblastic outgrowths than control embryos. Stagi ng embryonic development at the time of flushing, however, revealed re tarded embryo development in vivo in hormone-treated mice. After corre lation with embryonic stage at the beginning of the culture, there was no difference in the size of trophoblastic outgrowths. Conclusion: Tr eatment with gonadotropins impaired implantation and embryonic/fetal d evelopment. Changes in maternal milieu, rather than in embryo quality, may be responsible for the adverse effects observed.