Figure 3.

O₃ exposure causes epithelial damage in the upper airways. Light photomicrographs of the respiratory epithelium lining the axial airway of the left lung lobe from mice exposed to 0 (A,D,G,J), 1 (B,E,H,K) or 2 ppm (C,F,I,L) ozone. Tissues were histochemically stained with hematoxylin and eosin (A, B, C) or immunohistochemically stained for (D, E, F) FOXJ1, (G, H, I) club cell secretory protein (CCSP), or (J, K, L) proliferating cell nuclear antigen (PCNA). Abbreviations: a, alveolar parenchyma; arrow *, exfoliating epithelium; arrow C (red chromogen), CCSP; arrow F (brown chromogen), FOXJ1; arrow P (brown chromogen), PCNA; e, respiratory epithelium; sm, airway smooth muscle.