Metabolism and Glycogen Formation in the Liver of the Chicken Embryo

T H E investigations of Dalton (1937) and of Lee (1951) have shown that glycogen appears in the liver of the chicken embryo at 7-8 days' incubation and before the formation of insulin by the islets of Langerhans at 11-12 days (Potvin & Aron, 1927). Further, Dalton (1937) has shown that when livers of embryos of 3 days' incubation were transplanted on to the chorio-allantoic membrane of 11-13day hosts there was no acceleration of glycogen formation, althought it can be presumed that the transplanted livers were under the influence of insulin and other hormones in the blood-stream of the host. It is possible, therefore, that the first formation of glycogen is relatively independent of factors reaching the liver by way of the blood-stream and to be related more to events originating within the liver cells themselves. Such a possibility is in accordance with the results obtained in cultures of embryonic liver by Nordmann (1929), who showed that the formation of glycogen was, to a large extent, independent of the composition of the culture medium. If the initial deposition of glycogen is related to changes in the liver cells it is possible that the glycogen deposition is associated with loss of the ability to break down carbohydrate, storage of carbohydrate replacing its utilization. This possibility has been investigated by comparing, at different stages of development, the glycogen content and the carbohydrate metabolism of the developing liver in the chick embryo.