Abstract

The author carried out light microscopic and electron microscopic studies of alveolar capillary endothelial cells of rabbits after inhalation of pure oxygen in order to investigate oxygen toxicity on the endothelial cells and periodically observed after inhalation for 24,48,72,96, and 120 hours. The results were as follows. Light microscopically, congestion, edema, focal hemorrhage, and focal inflammatory infiltrates occurred within 24 hours of oxygen inhalation. Capillary proliferation and thickening of alveolar septa occurred at 72 hours of inhalation. Over 96 hours of inhalation thrombosis and focal necrosis appeared. Electron microscopically, pseudopod formation at 24 hours; mild swelling of Golgi apparatus and vacuolization of cytoplasm at 72 hours; loss of pseudopods, destruction and bleb formation of cell membrane, mitochondrial swelling, vacuolization of cytoplasm, and necrosis over 96 hours after oxygen inhalation appeared. Severity of degradation was more pronounced in the plasma membrane than in the cell organelles. From the above results, it is conceived that the endothelial cells fall in irritable state within 24 hours of pure oxygen inhalation and have irreversible injury over 96 hours of inhalation and that primary site of injury induced by oxygen toxicity is plasma membrane.