Physiological effects of trypan blue on chick embryos

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, CO2 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.