A micrograph of rat lung following intestinal ischemia and reperfusion. The black areas are the respiratory alveoli where air comes in contact with the gas exchange epithelium of the lung. The red cells are neutrophils attached to the capillary walls in the alveolar walls, and the blue is a localization for ICAM-1 (a necessary endothelial cell adhesion molecule for neutrophil binding). The green stain is FITC-labeled albumin which marks the vascular space. After intestinal ischemia and reperfusion, albumin leaks into the interstitial space of the alveolar wall, interfering with gas exchange. This image was collected from a 200 mm vibroslice section of rat lung on a BioRad MRC1024 scanning laser confocal microscope.