Histopathology of cardiopulmonary phase of MAPV infection in deer mice. Control lung (day 14) shows clear airways (bronchiole, B) and air spaces, normal vessels (pulmonary artery, PA) and normal thickness of interstitium (a, 200×). Lungs 14 days PI show alveolar hemorrhage, edema, and mild interstitial pneumonia (b, 100×). Lungs at 14 days PI show prominent perivascular (portal vein, PV, and artery, PA) neutrophilic infiltrates with mild interstitial pneumonia (c, 400×; d, 200×). Control heart shows a normal coronary artery and surrounding myocardium (e, 200×). Left atrium 7 days PI shows endothelial hypertrophy and hyperplasia with lymphocyte infiltration into subjacent myocardium with sarcoplasmic hyalinization and vacuolation of sarcoplasm with loss of cross striations (f, 400×). At 56 days PI, coronary artery (CA) with hypertrophic endothelium and perivascular edema, interstitial lymphocytic myocarditis and cardimyocyte degeneration/necrosis (g, 400×) and necrotic cardiomyocytes appear rounded up with hyperesinophilic sarcoplasm and pyknotic nuclei (h, 400×). Control liver shows intact limiting plate around normal portal vessels, hepatic artery (HA) and bile ductile (BD) (i, 200×). Focal disruption of portal vein (PV) endothelium (arrows) with lymphocytes percolating the limiting plate (LP) into the surrounding parenchyma mixed with a few neutrophils (j, 400×). Stain, hematoxylin-eosin.