THE LETHAL EFFECT OF ENDOTOXINS ON THE CHICK EMBRYO

Inoculation of the CAM of the 10-day chick embryo with endotoxin preparations derived from the meningococcus and other Gram-negative microorganisms has been shown to result in multiple hemorrhages and death of the embryo within a few hours. Evidence has been presented to indicate that this lethal effect is specific for the general class of endotoxins derived from Gram-negative bacteria. Susceptibility to endotoxin was maximal in 10-day old embryos, and younger or older embryos showed little or no response. The optimal incubation temperature for the effect of endotoxin was 39.5°C., and embryos incubated at 28°C. were completely protected. The lethal effect was prevented by small amounts of cortisone, hydrocortisone, and 9-alpha fluorohydrocortisone, but not by cholesterol, desoxycorticosterone, or 1-dehydrocortisone.