Gpr56 is required for myelin stability. (A–D) Serial scanning EM images (350, 100 nm apart) of WT and Gpr56^−/− mouse SN on P90 (n = 3 animals per genotype) were acquired and reconstructed to generate the WT and Gpr56^−/− models shown in A and C, respectively. Single sections taken from multiple locations along the nerve (1–4) are shown below each model (dashed lines show approximate locations). The percentage of axons with abnormal myelin profiles was calculated per section over a 15-µm distance for the WT (B) and Gpr56 mutant (D) reconstruction and is graphed to show the percentage of abnormalities per section (green line), the average percentage of abnormalities over all sections (black line) and the cumulative percentage of abnormalities (percentage of axons that show at least one abnormality over 15 µm [blue line]).