Figure 6: Morphological characteristics of group 4. (a) Group 4: infiltrate. Numerous cells of infiltrate and newly formed vessels. Arterioles are marked with arrows. (b) Group 4: penumbra. Extravasate formed by separated erythrocytes at the boundary between the penumbra and infiltrate. (c) Group 4: infiltrate. Macrophages with pale and stained granules. (d) Group 4: penumbra. Newly formed blood vessel is marked with a red arrow, and macrophages in the vessel wall are marked with black arrows. Hypertrophied vessel wall containing macrophages with dark cytoplasm. Semi-thin section. The scale bars are 100 μm in (a) and (b), 30 μm in (c), and 20 μm in (d).