4.1 A large bronchiole at the centre with its epithelial lining (white arrows, respiratory-type, cylindrical epithelium) and smooth muscle tissue (green arrows) around its wall. Alveoli filled with inflammatory exhudate (asterisks) instead of air. The exhudate has come out of the capillaries in the diaphragms (arrowheads) between the alveoli.
4.2 Congested capillaries (red arrows) and inflammatory exhudate within alveoli (asterisks).
4.3 Contents of the inflammatory exhudate: amorphous ( ie, fibrin, grey arrows) and cellular [neutrophils, purple arrows and mononuclear phagocytes (macrophages, light blue arrows)].
4.4 Abscess formation as a complication of lobular pneumonia due to pneumoniococcus infection. Pus in the centre ( area of liquefaction necrosis, pink asterisk ) a basophilic zone of neutrophils (purple asterisk) and an outer zone of vascularized connective tissue ( oil-coloured asterisk) with blood vessels (red arrows).
4.5 Pus in the centre of the abscess. Eosinophilic liquefaction necrosis and neutrophils’ nuclear dust (black arrows).