Developmental aspects of hexose metabolism in Bufo bufo

Due to the close correlation between glucose mobilization and utilization within animal tissues, in this paper, the stages of appearance of phosphorylase, glucose-6-phosphatase and hexokinase as well as the levels of some intermediates of glucose metabolism have been investigated during Bufo bufo development. Phosphorylase first appears at stage 13 and is dominant in the neural part of the embryo, but, after this stage, increases relatively more in the nonneural one. Hexokinase appears at stage 17 and glucose-6-phosphatase soon after. Phosphorylase appearance at stage 13 is correlated with an increase of lactate content in the embryo; this may indicate a metabolization of hexoses. On this basis, the subsequent appearance of hexokinase and glucose-6-phosphatase activities also seems coherent with hexose mobilization and utilization within embryo. No direct causative factor for the changes observed was evident.