[Free radical processes in the embryogenesis of Anura]

The localization of free radical processes and changes in their level during the common frog development have been studied by means of grafted copolymerisation and autoradiography. The maps of distribution of relative concentrations of free radicals were obtained for the beginning of cleavage, blastula, gastrula and neurula. The distinct regionalization was found in the beginning of cleavage: the concentration of the free radicals in the cortical layer and dorsal half of embryo is lower than in the central area and ventral half, resp. At the early blastula stage this regionalization is preserved in its general features. The region of embryo characterized by active free radical processes corresponds to the presumptive endo- and mesoderm in the period of inductive interaction. The possible participation of regional changes in oxidative metabolism in the fertilized egg in the determination of cytoplasmic localization of morphogenetic potencies is discussed. At the later stages there were variations observed in free radicals concentration, which are discussed as being related to the determination and morphogenesis of some rudiments of embryo. A local rise of free radicals concentration was also found out in the eye rudiment just before the onset of its components differentiation.