Histopathology of lungs of mice inoculated with M virus (a–d) or F virus (e–h).

<p>Lung samples of M and F virus-infected mice were used for histopathological H&E examination at the indicated days post-infection. ba r = 50 µm. Lung of mouse inoculated with M virus, a) 2 dpi. Mild congestion and diffuse lymphoid and phagocytic cells infiltrates in the interstitium. b) 4 dpi. Moderate thickened of interalveolar walls c) 7 dpi. Interstitial pneumonia with moderate proliferation of pneumocytes type II. d) 14 dpi. Interstitial pneumonia with thickened interalveolar walls. Lung of mouse inoculated with F virus, e) 2 dpi. Thickened interalveolar walls with consolidation of the pulmonary parenchima (interstitial pneumonia). f) 4 dpi. Moderate increase of interstitial macrophages. g) 7 dpi. Increase of macrophages and syncitial cells formation. h) 14 dpi. Severe hyperplasia of phagocytic cells in the interstitium. The arrows show some examples of the lesion indicated in each case.