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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 environment 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, however, 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.

Ten-day chick embryos (1) received yolk sac injections of 0.1 ml of 1.5% trypan blue in sterile saline, (2) received 0.1 ml of sterile saline or ( 3 ) were handled and returned to the incubator and examined five hours later. Trypan blue treated embryos exhibited decreased survival rate and significant decreases in plasma glucose, chloride, Con content and blood pH. Plasma potassium and embryonic wet weight were significantly elevated, but little change occurred in plasma sodium or hematocrit. Embryos frequently exhibited hemorrhaging after treatment. Saline treatment caused a small but significant decrease in plasma chloride and only a slight decrease in survival rate.The immediate response to trypan blue was markedly similar to that of hypoxia, presenting additional evidence in support of the view that trypan blue may interfere with the normal oxygen consumption of the embryo.

Chick embryos of 2-14 days of age were incubated in 13% oxygen for 5 days. Experimental embryos demonstrated lowered red blood cell levels, enhanced mean erythrocyte volumes, greater percentages of immature red blood cell stages, and depressed embryonic weights and stages when compared with their controls. Generally, embryos older than 13 days at the termination of the hypoxic incubation were less affected by the low oxygen treatment than younger ones. 1 The work reported in this communication was submitted to the Graduate School of the University of Maryland in partial fulfillment of the requirements for the degree of Doctor of Philosophy.

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