Developmental and cytogenetic effects of potassium dichromate on mouse embryos in vitro

Mouse blastocysts and egg cylinders were treated in vitro with potassium dichromate (K2Cr2O7, 5 × 10−7 to 2 × 10−6 M), and the effects on postimplantation development and induction of sister chromatid exchanges (SCEs) were determined. When blastocysts were treated for six days with 1 × 10−6 M K2Cr2O7, the number of embryos with growing inner cell masses (ICMs) and ICMs that were differentiated into primary endoderm and ectoderm were significantly reduced. The number of embryos forming trophoblast outgrowths was not reduced, but outgrowth formed in the presence of 2 × 10−6 M K2Cr2O7 were small and began to degenerate by the end of the treatment. Hatching and attachment were not affected at any concentration. The frequency of SCEs was significantly increased at ≥ 1 × 10−6 M. When egg cyclinders were treated with K2Cr2O7 for 24 hours, the number of embryos with blood islands, fusion of the allantois with the chorion, and beating heart was significantly reduced at all concentrations tested, and the crown‐rump lengths of embryos were significantly reduced at 1 to 2 × 10−6 M. The frequency of SCEs was increased in embryonic tissues of egg cylinders cultured in ≥ 1 × 10−6 M K2Cr2O7. Increased SCE frequencies were observed at lower concentrations in extraembryonic tissues, which had higher SCE frequencies than embryonic tissues at all concentrations tested. The correlation between developmental effects and SCE frequency suggests that cytogenetic damage may be largely responsible for the detrimental effects of dichromate on mouse embryos.