Congenital Heart Defects in Chick Embryos Subjected to Temperature Variations

Abstract
The effect of incubator temperature on mortality rates and on appearance of congenital malformations in white leghorn chicks and embryos was studied. The elevation of incubation temperature to 39.44°C led to a high mortality and to malformations in the eyes and the nervous system, as well as to abnormal torsion of the body axis. It did not produce any cardiac abnormalities, which would have been detected easily because the mortality peak occurred after the development of the heart was complete. Decreasing temperature of incubation to 35.83°C produced a high mortality rate and, very frequently, interventricular septal defects. These results and the possible mechanisms by which changes of temperature exert teratogenic effects are discussed.