Fig. 2.

Porcine lung tissue with different lesions. (a) Gross appearance of chronic CBP. Inset shows lung tissue with a bronchial pattern of pulmonary consolidation. (b) Suppurative bronchiolitis and concurrent epithelial hyperplasia (E). HE. Bar, 25 μm. (c) Oedematous flooding of alveoli. HE. Bar, 50 μm. (d) Thickening of alveolar septa by collagenous (blue) tissue. Masson's trichrome. Bar, 50 μm. (e) Alveolar polyp-like structures, P1 with a fibrinous core and P2 with cellular infiltrate. Both are covered by type I and type II pneumocytes as shown by immunohistochemical labelling for cytokeratin expression. Bar, 25 μm. (f) Alveolar polyp-like structure (P) with a collagenous core (blue). Masson's trichrome. Bar, 15 μm. (g) Focal necrotic encapsulated tissue with central mineralization (M). HE. Bar, 100 μm. (h) Mild thickening of alveolar septa from a pig in the control group. HE. Bar, 50 μm.