Modification of Teratogenic Action of Cortisone in Mice by Maternal Age, Maternal Weight and Litter Size

¹ From the Department of Genetics, McGill University, Montreal, Canada

Primigravid, hybrid female mice of a range of weights and ages were given injections of 2.5 mg cortisone acetate/day for 4 successive days beginning 11 1/3 days postconception. The frequency of offspring born with median cleft palate decreased with increasing maternal weight, advancing maternal age and increased litter sizes. Analysis of the data by multiple regression has shown that the cleft palate frequency depends on maternal weight, and that maternal age and litter size seem to play a role only because they are so highly correlated with maternal weight. In mice of constant parity, therefore, heavier animals are more resistant to the cleft palate-inducing properties of cortisone than lighter animals are. The possible role of maternal fat metabolism is discussed.