Fig. 2. Degenerating neurons and caspase-3 immunostaining 48 hr after HI. Dark-field images from 50 μm, Nissl-stained sections of parietal cortex (A), striatum (B), and CA1 hippocampus (C) on the ligated side. A columnar pattern of degenerating neurons was observed in parietal cortex (A). High-magnification images from the penumbra (A1) and ischemic core (A2) showed apoptotic cells with large, round, chromatin clumps (arrows, A1) and necrotic cells with small, punctate chromatin clumps (asterisks,A1, A2). The striatum showed a patchy pattern of clusters of normal and degenerating neurons (B). At higher magnification, apoptotic cells with large, chromatin clumps (arrows, B1) were observed. In CA1 (C), the bright ribbon of degenerating cells contained apoptotic (arrows,C1) and necrotic (asterisks,C1) cells. Caspase-3 immunoreactivity showed a granular and particulate pattern in damaged areas within cerebral cortex (A3), striatum (B2), and CA1 (C2). Noninjured areas, in right parietal cortex 0 hr after HI, at low (D) and high (A4,D1) magnification, showed only diffuse, nonparticulate background staining. Scale bars: A–D, 100 μm;A1–D1, 10 μm.