Endothelial lesions associated with gas bubble disease in fish

Two groups of healthy chinook salmon (Oncorhynchus tshawytscha) were experimentally exposed to gas supersaturated groundwater. Gross lesions consistent with gas bubble disease (GBD) developed. Vascular lesions associated with intravascular gas bubbles were examined with light and scanning electron microscopy. Dermal blood vessels containing gas bubbles were severely dilated. Additionally, the gas bubbles were spatially associated with endothelial lesions ranging from cellular degeneration to exfoliation. The resulting regions of exposed subendothelial connective tissue were sparsely covered by small unidentified adherent cells and strands of fibrin. In the light of these findings, the similarities in vascular pathology between GBD in fish and decompression disease in man are discussed, particularly with respect to the initiation of haemostatic disorders in both conditions.