[Glycogen phosphorylase isoenzymatic makeup changes in the liver of birds and mammals in ontogeny]

It was established by means of immunochemical titration that phosphorylase of the chickliver, beginning from the 8th day of embryogenesis, was represented by an isozyme, immunochemically identical or closely related to mammalian phosphorylase L. At the early stage of development (4th day) the chick embryo contained both isozyme L (ca. 60%) and isozyme, closely related to mammalian isozyme I. In the liver of 15 days old rat embryos the ratio of isozymes I and L equaled 1 : 2. It is suggested that the ratio of L and IL is close to 1 : 1. The isozyme IL is replaced for the isozyme L completely during the second ten day period of postnatal development.