FIGURE 7

Optic nerve myelination is normal in Sarm1 null mice. (A) Representative electron micrographs taken at x 3,000 (left hand side panels) and x 12000 (right hand side panels) magnification from adult Wt and Sarm1 KO optic nerves at postnatal day 60 (P60). There are no ultrastructural differences in the optic nerves of Sarm1 KO compared to those of Wt animals. Scale bar 5 μm (x 3,000) and 2 μm (x 12,000). (B) The total number of axons quantified per optic nerve profile are not significantly different between Wt, 41422 ± 1375 and Sarm1 KO, 40484 ± 786 (mean and SEM, n = 6 Wt; n = 5 KO; p = 0.9307). (C) The number of myelinated axons quantified in Wt, 38457 ± 1441 and Sarm1 KO, 38782 ± 852.9 optic nerves is similar (mean and SEM, n = 6 Wt; n = 5 KO; p = 0.4286). (D) The percentage of myelinated axons quantified in Wt, 92.8 ± 1.2 and Sarm1 KO, 95.9 ± 0.5 optic nerves is not significantly different (mean and SEM, n = 6 Wt; n = 5 KO; p = 0.0736). (E) Myelin sheath thickness as depicted by g-ratios is similar in both Wt, 0.757 ± 0.007 and Sarm1 KO, 0.757 ± 0.01 optic nerves (mean and SEM, n = 6; p = 0.9610). (F) Scatter plot of g-ratio as a function of axonal caliber in Wt optic nerves. (G) Scatter plot of g-ratio as a function of axonal caliber in Sarm1 KO optic nerves. (H) Relative mRNA expression for chemokine, oligodendrocyte and myelin genes in the P60 uninjured optic nerve of Wt and Sarm1 KO mice. All fold change values normalized to uninjured Wt optic nerve (n = 4; *p < 0.05, **p < 0.01). (I) Representative western blot image of optic nerve protein extracts shows no difference in levels of MBP, between Wt and Sarm1 KO nerves. (J) There is no significant difference in MBP expression between Wt and Sarm1 KO optic nerves (n = 6; p = 0.3939). The quantifications are normalized to the levels in uninjured Wt nerves, which are set as 1.