Airway architecture in normal and sensitized mice. General pulmonary architecture in the unsensitized (A) and sensitized (B) mice. (A) In all groups of unsensitized mice, lung parenchyma was clear, lacy, and essentially devoid of inflammatory cells. (B) In the lung parenchyma of sensitized mice, epithelial folding and distortion (F), lumen narrowing (L), goblet cell metaplasia (G), eosinophil infiltration (I), and subepithelial fibrosis (basement membrane thickening, T) are evident. All images were captured at a magnification of 40×.