Vascular hypervolemia and hematoma formation in chick embryos treated with trypan blue

The relationship between cardiovascular disturbances and the formation of hematomas in trypan blue-treated chick embryos was investigated. Hematocrits from Hamburger-Hamilton stage 15 and 16 embryos (8-10 hours after treatment at stage 13) were obtained. The hematocrit value from the treated embryos was significantly lower (P less than 0.001) than the values from controls. Unopened and saline-injected control values were not significantly different (P greater than 0.05). We interpret this to mean that there is excess circulating fluid volume in the treated embryos. The results of direct injection of measured volumes of fluid into the cardiovascular system of normally developing embryos (stages 15 and 16) provided evidence to suggest that the caudal dorsal aortae are susceptible to fluid-induced distension and rupture.