Embryonic characteristics in superovulated mouse strains. Comparative analyses of the incidence of chromosomal aberrations, morphological malformations, and mortality of embryos from two strains of superovulated mice

Superovulation was induced in an inbred (C3HeB/FeJ) and a random-bred (CD-1) strain of mice and pregnant females were serially sacrificed from 6-15 days of gestation. All embryos were examined chromosomally and by external morphology. A G-banding technique was used to detect specific chromosomal constitutions. The common types of chromosomal aberrations were monosomies and trisomies. Our results showed that the proportion of chromosomally abnormal embryos was significantly greater in the superovulated group of inbred mice, than in the spontaneously ovulating inbred group, an observation not made in the random-bred mice. In each strain, superovulation yielded a significantly higher proportion of morphologically malformed embryos, but no significant difference between strains with respect to this criterion was noted after superovulation. There was a significant increase in the post-implantation embryonic mortality in the random-bred strain but not in the inbred strain following superovulation. This study indicates that each strain has its intrinsic pattern with regard to the fate of embryos following superovulation.