DEVELOPMENT OF ANTIOXIDANT CAPACITY IN TISSUES OF THE CHICK-EMBRYO

The concentrations of vitamin E, vitamin A, selenium, reduced glutathi one and the activities of glutathione peroxidase and superoxide dismut ase were determined in the yolk, yolk sac membrane, liver and brain of the developing chick embryo. The changes in the concentrations of vit amins E and A in the yolk and liver during development were consistent with the occurrence of a preferential transfer of vitamin A from the yolk to the embryo before day 14 of incubation, whereas the main perio d of vitamin E transfer occurred later, during the last week of incuba tion. The concentrations of reduced glutathione in the yolk sac membra ne, liver and brain were similar at all developmental stages studied. However, the levels of the other measured antioxidant systems were ver y much higher in the liver than in the brain. Thus, in the newly hatch ed chick, the levels of vitamin E, vitamin A, selenium, glutathione pe roxidase and superoxide dismutase were, respectively, 58.0-, 174.7-, 3 .6-, 4.0- and 4.7- fold higher in the liver than in the brain when exp ressed on the basis of tissue fresh weight.