Effects of Thyroxin on Palatogenesis, Fetal Resorptions, and Fetal Weights in A/Jax Mice

¹ School of Dentistry, University of Pittsburgh, Pittsburgh, Pennsylvania

Thyroxin (0.1 mg.) given intramuscularly on the 11 and 12 day of gestation failed to alter the frequency of spontaneous cleft palate (CLCP), average number of fetuses, or average fetal weights per litter in A/Jax mice. It seemed neither to potentiate nor protect against the teratogenic effects of cortisone on mouse palatogenesis when given alone. However, in combination with a single dose of 10 mg. cortisone on 11 day of gestation it caused significantly higher incidence of fetal resorptions and reduction in average number of fetuses and fetal weights per litter. Within the limitation of the experimental design of this investigation, no significant reduction in the genetically determined spontaneous cleft lip was noted in thyroxin-treated mice as reported by others. This difference in experimental results may in part be attributed to the difference in the route of administration of the drug or the strain of mice employed.