Demyelination and remyelination in dorsal columns of wild type (WT) and NG2 null (KO) mice. Immunolabeling for MBP (green) and neurofilament (NF, red) reveals greater initial demyelination in wild type (A) compared to NG2 null spinal cord (D) during the first post-surgery week. However, better repair is seen in wild type (B and C) than in knockout (E and F) spinal cord at 6 weeks after surgery. The higher resolution images in C and F allow identification of NF-positive axons (red) associated with (arrowheads) or lacking association with (arrows) MBP-positive myelin (green) at 6 weeks post-injury. Quantification of white matter lesion volumes, defined as MBP-negative regions (see panels A, B, D and E), in wild type and NG2 null mice reveals larger lesions in wild type mice one week after lysolecithin injection, but diminished repair of lesions in NG2 null mice six weeks post-injury. Lesion volumes are expressed as mean values ± SD. (G). An increased number of demyelinated axons (H), determined by MBP and NF double labeling (see panels C and F), were present in the dorsal column of NG2 null mice 6 weeks after lysolecithin injection. Statistically significant differences are indicated by * < 0.05; ** < 0.01 when values for WT and KO mice are compared at the same time point; b < 0.01; c < 0.001 indicate statistically significant differences within the same genotype at 1 and 6 weeks after lysolecithin injection. Scale bar = 100 μm (A, B, D and E) and 8 μm (C and F).