Effects of hyperoxia on chick embryos injected with trypan blue

Ten‐day chick embryos (1) received yolk‐sac injections of 0.1 ml of 1.5% trypan blue in sterile saline, (2) were placed into a hyperoxic environ‐ment of 45% oxygen, or (3) were exposed to trypan blue plus hyperoxia, and examined 5 h later. Hyperoxia virtually eliminated trypan blue‐induced mortality and caused considerable reduction in the appearance of hemorrhages. Blood pH and plasma glucose and potassium concentrations remained relatively stable, compared to embryos not subjected to hyperoxia. Embryonic wet weight, how‐ever, increased. It is suggested that hyperoxia functioned protectively by either (1) acting against electron transport inhibition or (2) permitting the normal passage of oxygen to lysosomes.