Figure 2.

Wallerian degeneration and mitochondrial degeneration in axon for rat’s distal nerve stump. a, Representative images of toluidine blue staining, immunohistochemistry (NF-H), electron microscopy, before (pre) and 1, 2, and 14 d after axotomy. Immunohistochemistry was obtained the same results for three individuals. Scale bar, * 10 μm, ** 2 μm. Arrows, myelinated axon; arrowheads, demyelinated Schwann cell. b, Quantification of the myelinated axon. c, d, Quantification of the G-ratio [c: cumulative G-ratio per individual, d: scatter plot, Spearman’s rank correlation coefficient and p values showing G-ratio of individual myelinated axons against axon diameter (n = 400)]. The histologic WD was observed significantly from 2 d after axotomy. In axons, before (pre) and 1 and 2 d after axotomy were evaluated, except for after 14 d with completely collapsed axon morphology (n = 4 rat per group). e, Representative images of mitochondrial findings, before (pre) and 1, 2, and 14 d after axotomy. Evaluation was performed in axons and Schwann cells separately. Scale bar, * 200 nm. f, Violin plot of mitochondrial diameter (nm; n = 200). Cumulative mitochondria diameter per individual are also shown (n = 4 rat per group). g, Quantitative analysis of atypical mitochondria (%; n = 4 rat per group). In axons, mitochondria were significantly degenerated from 1 d after axotomy, whereas in Schwann cells, mitochondria were not significantly degenerated until 14 d after axotomy. All histologic evaluations were performed 3 mm distal to the sectional end and corresponding uninjured nerve. Error bars indicate SD; *p < 0.05, ***p < 0.001, one-way ANOVA followed by the Tukey’s post hoc test (for comparison of axons and Schwann cells, respectively).