PGN challenge induces peripheral organ congestion and fibrin deposition. Pathologic changes in peripheral tissues at end point were evaluated after histologic staining with H&E (top) or PTAH (middle and bottom) for detection of fibrin deposits. Images were acquired on an upright Nikon Eclipse E800M microscope equipped with an Omax high-speed digital camera using the Omax ToupView software. Representative lung and kidney micrographs from PGN-challenged baboons are shown. (A-C) Pulmonary pathologic changes are more prominent in the high-dose (left panel) than low-dose group (right panel). Liquid-filled (*) alveoli (av) and fibrin deposits (arrows) are highlighted throughout the figure. An example of leukocyte aggregates obstructing the pulmonary microvasculature in the high-dose PGN challenge is depicted in the left panel inset in panel A. Intravascular (left panel) and extravascular (right panel) fibrin deposits are easier identified at higher magnification in panel C. (D-F) Renal pathology is more prominent in the high-dose PGN challenge (left panels) than the low-dose group (right panels). Glomeruli (G) and tubules (T) are exemplified throughout the figure. Fibrin deposition (arrows) in either tubular (left) or glomerular (G) areas is highlighted at higher magnification in panel F. Scale bars represent 100 µm.