PAS staining for goblet cells in the lung tissues treated with ZnONP at 150 cm2
/rat. Each panel is composed of low power view (left, 100×) and high power view of bronchiolar epithelium (right, 400×). (A) Vehicle control; (B) ZnONP at 24 h; (C) ZnONP at 1 wk; (D) ZnONP at 4 wks; Percentage of PAS-positive cells in the bronchus (> 1 mm in diameter) (E) and bronchiole (< 1 mm in diameter) (F). Goblet cells (arrow) peaked at 1 wk and still present 4 wks after ZnONP instillation. Each data point represents an independent bronchus or bronchiole in the lung tissues. Significance versus vehicle control: * p < 0.05, ** p < 0.01, # p < 0.001.