Figure 5

Photomicrographs of H&E-stained ovine right lung lower lobe sections from experiments over 24 hours. Left: sections magnified ×100. Right: fields limited by squares are magnified ×400. (a) Sheep exposed to recombinant human activated protein C (rhAPC) alone, displaying no gross changes from normal. (b) Sheep exposed to intravenous infusion of lipopolysaccharide (LPS). Hyperemia and intravascular accumulation and extravasation of neutrophils (arrows) are accompanied by interstitial edema and thickening of interalveolar and interlobular (ias and ils) septa as well as injury to the alveolar lining with formation of hyaline membranes (hm). (c) Sheep treated with infusion of rhAPC from 4 hours after the commencement of LPS. Interlobular and interalveolar septa are predominantly infiltrated with lymphocytes (arrows) and interalveolar septa have returned to nearly normal thickness. Hyaline membranes are partly dissolved.