Treatment with gonadotropins impaired implantation and fetal development in mice

The effect of gonadotropins on implantation and fetal development in mice was investigated by superovulation with pregnant mare serum gonadotropin and human chorionic gonadotropin. In a previous study fetal growth was found to be highly retarded.

Assessment of implantation in vivo revealed that late implantation did occur. Gestational length was highly extended, the mean number of live fetuses per pregnant mouse was lower and their mean weight significantly reduced. In vitro experiments revealed no significant difference in the rate of blastocyst adhesion and trophoblast outgrowth development. Immunohistochemical staining, however, showed that blastocysts from superovulated mice had smaller trophoblastic outgrowths than control embryos. Staging embryonic development at the time of flushing, however, revealed retarded embryo development in vivo in hormone-treated mice. After correlation with embryonic stage at the beginning of the culture, there was no difference in the size of trophoblastic outgrowths.

Treatment with gonadotropins impaired implantation and embryonic/fetal development. Changes in maternal milieu, rather than in embryo quality, may be responsible for the adverse effects observed.