Fig. 8.

Regional changes in axonal area and neurofilament number in myelin-deficient mutant mice. Cross-sectional areas and neurofilament number per 1000 axons of representative caliber sizes were determined at the 50 μm level (n = 8062 or 1016 axons for area or neurofilaments, respectively) and 700 μm level (n = 5707 or 547 axons, respectively) of the optic nerve as described in Figure 3. Data points for unmyelinated (u), oligodendrocyte-wrapped (w), and myelinated (m) populations are expressed as a percentage of the values obtained for these axons analyzed at the 50 μm level and their respective SEM. The axonal area and neurofilament number in the oligodendrocyte- wrapped and myelinated axons in the mutant mice do not differ significantly as shown by the Wilcoxon/Kruskal–Wallis test (p = 0.21–0.73) (see Materials and Methods).