Figure 6.

Consolidation in the lungs composed of both large numbers of macrophages and extensive type II pneumocyte hyperplasia. A: Representative image of lung at 7 days post inoculation (DPI), showing severe consolidation, including type II pneumocyte hyperplasia with large atypical epithelial cells and multinucleated syncytial cells (arrow). Hematoxylin and eosin staining was used. B: Similar area of consolidation within the lungs at 7 DPI with immunostaining to detect pan-cytokeratin (red chromogen) and Iba-1 (brown chromogen) revealed that the large, atypical cells and multinucleated cells were epithelial, whereas the macrophages were within the alveolar and interstitial spaces. Hematoxylin counterstain was used. Original magnification, ×40 (A and B).