The Inheritance of Susceptibility to the Teratogenic Action of Cortisone in Mice.

T has been found (FRASER and FAINSTAT 1951) that pregnant mice given I cortisone during gestation will give birth to offspring a certain proportion of which have cleft palates. The frequency with which this deformity appears was observed to depend on : 1) the genotype of the treated animal, strain A being “ susceptible,” C57BL relatively ‘’ resistant,” to this effect of cortisone; 2) the dose of the hormone administered, too small an amount being ineffective in producing cleft palates, too great an amount causing resorption of the entire litter; and 3) the time during the gestation period when the animal was treated. The investigation reported here has provided fiirther observations on the genetics of susceptibility to the teratogenic effects of cortisone.