A, B, D, E) Electron micrographs of coronal sections of WT and Twitcher sciatic nerves at P12 and P30 show a decrease in axonal diameter in the Twitcher fibers (A) as compared to age-matched WT fibers (B). Severely demyelinated and abundant small diameter axons were clearly observed in older (P30) Twitcher nerves (D). All images are at the same magnification (bar in A=2 μm). Arrows and asterisk in D point to myelinated axons and edema, respectively. C, F) Distribution profiles based on axonal diameter showed a growing increase in small-caliber axons. A minimum of 50 axons was counted per each nerve (n=3 nerves/time point/genotype). Data were analyzed by ANOVA/post hoc paired test. p<0.05.