Figure 4.

Mutant myelin sheaths are significantly thinner than control, but the specific protein composition of the myelin in mutant mice is not affected. A, Graph shows the linear regressions of fiber measurements performed in the spinal cord for control (straight lines) and mutant (dashed lines) mice. Control and mutant linear regressions are significantly different (p = 0.013), and the average growth ratio in mutant spinal cords is significantly higher (0.8) than in controls (0.75) (p = 0.039). For the growth ratio/linear regression analysis, the Welch two-sample t test and the Wilcoxon rank sum test were applied. B, Western blot analysis of P14 and P24 mutant and control spinal cord lysates shows no differences in the relative amounts of the myelin proteins PLP, CNP, MBP, MAG, and MOG. Actin levels confirm equal protein loading. Western blots were performed at least two times. C, The periodicity of the compact myelin sheath in the mutant spinal cord is not altered. Major dense line spacing in controls and mutants is 15 nm. D, Axon diameters of control and mutant P24 spinal cord anterolateral fiber tracts were assigned to four pre-established size categories. No significant differences were found between control and mutant axons in either category. Values are shown as mean of the measurements taken from three control and mutant mice. Error bars indicate SEs. Student's t tests were used to determine significance.