Comparison of normal lungs and pneumonia with necrotic areas and bacterial colonies in M. gallisepticum -infected birds. Figure 4A: The lung parenchyma of a partridge from the control group. Parabronchial lumen (1) and wall with bundles of smooth muscle tissue (2) is surrounded by air and blood capillaries. H&E stain.
Figure 4B: A focus of necrotic pneumonia with secondary bacterial colonisation (*) surrounded by a thin layer of heterophils and lymphocytes in a partridge infected with M. gallisepticum. H&E stain.