Effect of temperature alterations on liver and cardiac glycogen in the chick embryo

1. 1. Chilling chick embryos at 10, 14, 18 and 20 days of incubation to 25°C until killed resulted in an initial increase in liver glycogen accompanied by a decrease in cardiac glycogen. 2. 2. Within hours liver glycogen returned to near normal levels accompanied by an increase of cardiac glycogen to or above control values. 3. 3. Increasing temperature to 41–43°C on the tenth day resulted in decreased cardiac glycogen 24 and 48 hr later. 4. 4. In 14 day embryos a decrease in liver glycogen occurred within 1 hr after the beginning of treatment.