Proliferation of IBA-1 immunoreactive macrophages/microglial cells in the injured spinal cord. Sections of injured spinal cord were evaluated for BrdU incorporation (green) and IBA-1 labeling (red) 7 days after injury (3 days after BrdU injection). Compared to wild type animals (A-C), fewer proliferating IBA-1-positive cells are seen in NG2 null mice (D-F). Boundaries of demyelinated lesions are indicated by white dotted lines in C and F. In NG2 null mice, IBA-1/BrdU double-labeled cells (arrows) remain outside the lesion to a greater extent than in wild type mice. Scale bar = 100 μm.