Comparative pathology of Prudhoe Bay crude oil and inert shell sealants in chicken embryos

Pathological changes and body weights were compared in 9-day-old chicken embryos exposed to Prudhoe Bay Crude Oil (PBCO), pharmaceutical mineral oil, or a sealing film on the eggshell. Embryos exposed to 10 or 20 microliters PBCO developed marked ascites or subcutaneous edema, extensive liver necrosis, dilation of the heart, and cellular casts and mineralization in renal tubules. Wet and dry body weights were normal or above normal in embryos exposed to PBCO. No changes were found in embryos exposed to 10 microliters mineral oil; embryos exposed to 20 microliters mineral oil had slight dilation of the heart. Very few embryos survived in eggs that were wrapped in sealing film. All embryos that did survive had greatly reduced body weight and marked dilation of the heart. Four of these embryos had vacuolation of hepatocytes at the surface of the liver, one had superficial liver necrosis, and one embryo had slight ascites. These results indicate that the mechanism of the toxic action of PBCO on the avian embryo involves more than simple physical sealing of the shell.