Figure 4

iNOS and nitrotyrosine immunoreactivity at the cold injury site. iNOS: At 12 hours the cold injury site shows necrosis in the neuropil (a). Marked iNOS immunoreactivity is present in polymorphonuclear leukocytes (arrowheads) and in the endothelium of the overlying pial vein (arrow). b, At day 2, iNOS immunoreactivity is present in the endothelium of an intracerebral venule, in polymorphonuclear leukocytes (arrowheads), and in most macrophages present (arrows). c, At day 4, iNOS immunoreactivity is present in the multinucleate endothelial cells at the lesion site (arrows) and in the endothelium and smooth muscle cells of the pial artery overlying the lesion. d, At day 6, mild to moderate (1+ to 2+) iNOS immunoreactivity is present in the hyperplastic smooth muscle cells of the pial arteries overlying the lesion site. e, At 3 hours, cytoplasmic nitrotyrosine immunoreactivity is present in neurons within the lesion and in the surrounding extracellular spaces. f, At 4 days, cytoplasmic nitrotyrosine immunoreactivity is present in macrophages (arrows) and polymorphonuclear leukocytes (arrowheads). The neuropil shows diffuse nitrotyrosine immunoreactivity. Magnification: a, b, e, and f, × 500; c and d, × 250.