Figure 1. Pulmonary histopathology of WT mice 5 h following acid and gastric particulate aspiration.

Normal saline (saline) + HCl, pH = 1.25 (acid), 7.5 mg/ml small, non-acidified gastric particles (part.), or 7.5 mg/ml part. + HCl, pH = 1.25 (acid+part.) was instilled into the lungs, intratracheally (i.t.), of WT mice. The mice were sacrificed 5 h later, and lung sections were analyzed by H&E. Boxes in the left column images (bars = 100 μm) indicate areas that are magnified in their respective right column images (bars = 25 μm). A & B) uninjured; C & D) In acid-injured mice, necrotic cells and debris within the bronchial and bronchiolar airspaces (arrows) with moderate PMN infiltrate and denuded bronchiolar epithelium (arrow heads) were observed; E & F) Administration of particles alone resulted in generalized PMN infiltration and focal areas of dense PMN accumulation in the alveolar spaces and in some of the bronchioles without evidence of necrotic cells; G & H) In mice administered acid+part., both PMN infiltration similar to mice administered particles alone and necrotic bronchial epithelial cells (arrows) were observed. Images shown are representative of lungs from 2 – 3 mice from 3 independent experiments.