Lung histopathology of SAD mice exposed to hypoxia/reoxygenation and effect of inhaled NO. In the left panels are shown representative examples of SAD mouse lungs exposed to hypoxia/reoxygenation for 46 hours. (A) More than 50% of the bronchus lumen (B) is filled with mucus; (C), a constricted vessel (V) is evident for the large surrounding clear area containing many inflammatory cells; (E), a small vessel filled with a thrombus (T) is shown. (B) Representative section of a SAD mouse lung exposed to hypoxia/reoxygenation and inhaled NO. Here the bronchus lumen (B) is devoid of mucus, the constriction of the vessel (V) is much less intense than that seen in panel C, as evident by the clear area around the vessel whose thickness is not superior to that of the vessel wall, associated with a mild inflammatory infiltrate. Panel D exemplifies the lung histology of SAD mice under normoxia. The lumen of the bronchus (B) is devoid of mucus; the neighboring vessel (V) is not constricted and contains few red blood cells. There is no inflammatory infiltrate. (F) Example of lung histopathology of wild-type mice exposed to 46 hours hypoxia/reoxygenation. The lumen of the bronchus (B) is devoid of mucus; the neighboring vessel (V), filled with erythrocytes, is constricted, with a mild inflammatory infiltrate (arrowhead) in the clear area surrounding the vessel. All tissue sections are stained with hematoxylin and eosin, and the original magnification is × 250 (with the exception of panel A, × 200).