Metabolism and Glycogen Formation in the Liver of the Chicken Embryo

Abstract

ABSTRACT In the liver of the chicken embryo the earliest stage at which glycogen was regularly found was a group of embryos of which the eye diameter was 4·3-4·9 mm. The mean incubation time of these embryos was 6·9 ± 0·14 days. The appearance of glycogen was associated with changes in the metabolism of the isolated liver in a glucose-containing medium; mean values for the rate of respiration fell from 1·02 to 0±53 μl. oxygen/c.mm. tissue/hr., and the mean values for the respiratory quotient from 0·84 to 0·68. In both cases the lower level had undergone no further significant alteration by the tenth day of incubation. Observations in a medium to which glucose had not been added showed that before the appearance of glycogen omission of glucose caused a decrease in the mean rate of respiration and in the mean value for the respiratory quotient. These changes were not observed after glycogen had appeared. From these changes it is concluded that the appearance of glycogen in the liver of the chicken embryo is associated with the loss of enzymatic activity necessary for the respiratory catabolism of glucose. After the appearance of glycogen in the liver cells the respiratory quotient of the isolated liver suggests that uric acid formation occurs. This possibility has been discussed.