Fig. 2. Activated caspase-3 and caspase-8 are located in the infarct core 1 hr after MCAO. A, Active caspase-3 (CM1 antibodies) labeling encompasses layers IV–V, in which the first signs of structural alterations are observed. B, No labeling is observed on sections treated with preadsorbed antibodies.C, On an adjacent section, active caspase-8 (SK440 antibodies) is more widely distributed but is also observed in cells of layers IV–V. D, No labeling is observed on sections treated with preadsorbed antibodies. Arrows inA and C indicate similar blood vessels on the adjacent sections. I–VI indicate the cytoarchitectural divisions of the mouse parietal cortex. E, F, Cells labeled for the p20 protein (red, arrows) consistently display chromatin condensation (blue, bisbenzimide). P20-negative cells have a normal nuclear aspect (arrowheads). G, Active caspase-8 (p18) in neurons of layer IV. H, Confocal microscopy confirmed the colocalization of p20 (red) and p18 (green) in layer IV. Arrowheads inH point to tissular alterations characteristic of the core. Scale bars: A, C, 240 μm;B, D, 75 μm; E,F, 7.5 μm; G, 20 μm;H, 24 μm.