Mouse strain and quality control testing: improved sensitivity of the mouse embryo assay with embryos from outbred mice

Objective To determine the relative sensitivities of embryos from different strains of mice to in vitro stress. Design Laboratory experiment with embryos from different mouse strains. Setting University hospital–based fertility clinic. Animal(s) Mice. Intervention(s) Fresh one-cell embryos from outbred (CF1), inbred (FVB), F1 hybrid (B6/CBA), and cryopreserved F2 hybrid embryos (bcl/B6 × B6/bcl) compared in a mouse embryo assay (MEA) using six doses of each of three in vitro stressors: cumene hydroperoxide in mineral oil, Triton X-100 (TX-100) in media, and hyperosmolality. Main Outcome Measure(s) Blastocyst rate at 96 hours. Result(s) All studies were conducted in triplicate; data were analyzed with chi-square analysis based on fitting a logistic regression model. Both cumene hydroperoxide and Triton X-100 affected blastocyst formation in the outbred strain at concentrations that were less than half of the concentration that affected the other strains. The total number of cells was affected by the treatments in all strains. Conclusion(s) Outbred CF1 embryos are genetically diverse and more sensitive to toxins than either inbred or hybrid mouse embryos. Outbred embryos provide an additional tool for effective quality-control testing.