Reduction of 6‐aminonicotinamide teratogenicity in mice by etherization,

In an experiment involving selection for cleft lip in which pregnant mice were treated with 6‐aminonicotinamide (6‐AN) to induce this malformation, some were lightly anesthetized with ether to make them easier to handle at the time of treatment. In the first experiment etherization significantly lowered the frequency of malformed embryos from 51.7 to 26.2%, and of induced cleft lip from 23.9 to 3.3%. The resorption frequency was also significantly reduced from 38.5 to 22.4%. A second experiment under more controlled conditions in a later generation of the selection experiment gave results consistent with those of the first experiment. This finding must be taken into consideration whenever anesthesia is used in teratological experiments.