Skip to main content
. 2022 Feb;192(2):195–207. doi: 10.1016/j.ajpath.2021.10.009

Figure 3.

Figure 3

Progressive morphologic alterations in lung over time. Mock-inoculated (intranasal saline alone) animals that served as uninfected controls had no lesions identified by histologic examination. At 2 days post inoculation (DPI): Lung lesions included intraluminal neutrophilic infiltrates and necrotic cellular debris (arrow). At 4 DPI: Lesions included areas of consolidation (asterisk) consisting of type II pneumocyte hyperplasia (arrow), numerous intra-alveolar macrophages, neutrophils, necrotic cellular debris, and eosinophilic fibrinous exudate (circled). At 7 DPI: Extensive areas of pulmonary consolidation were present (asterisks) with atypical proliferative type II pneumocyte hyperplasia (arrow), abundant intra-alveolar macrophages, degenerate neutrophils, and fewer lymphocytes. At 14 DPI: There were multiple scattered areas of residual type II pneumocyte hyperplasia (arrow). At 28 DPI: Scattered small clusters of type II pneumocyte hyperplasia with cuboidal epithelial cells remained (arrow). Original magnification, ×2 (top panels); ×20 (bottom panel, control); ×40 (bottom panels, hematoxylin and eosin staining).