Fig. 2.

Exposure to Al₂O₃ NPs led to experimental COPD in a murine model. a Representative images of normal alveolar area and emphysema. The images on the right bottom of each panel are magnified (400) of area from the original one. b Lm was significantly increased in Al₂O₃ NPs-exposed mouse lungs (n = 36, ^*** P < 0.001). c Representative images of PAS staining, the PAS⁺ cells suggested hypersecretion of airway epithelial cells (shown by arrows). d Representative images of Masson’s Trichorome staining. Deposit of collagen around airway was stained purple. e Representative images of TUNEL staining and percentage of TUNEL⁺ cells. The TUNEL⁺ cells were shown by arrows. (n = 30, ^*** P < 0.001, compared with control group)