Representative T2-weighted, axial magnetic resonance image 24 h after middle cerebral artery occlusion with reperfusion.The hyperintensity corresponds to the ischemic area. Tissue was obtained from the ischemic core (black circles), the border of the ischemic lesion (black squares) and areas corresponding to the ischemic core (white circles) and its border (white squares) in the contralateral, non-ischemic hemisphere.