Myelin staining and electron microscopy reveal the presence of persistent aberrant myelin patterns in the brain of CX3CR1^−/− mice after cuprizone feeding. (A–D) Myelin staining with 0.5 mM 1,1′-Dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate (DiI) (red) and Iba1-immunoreactive staining (green). (E–J) Imaging at (E, F, and G) low or (H, I, and J) high magnifications of myelin state in representative sagittal microsections of the corpus callosum of either (E and H) untreated WT or (F and I) treated WT and (G and J) CX3CR1^−/− with a cuprizone diet for 5 wk. (K–M) High powered magnification of aberrant myelin patterns frequently seen in the corpus callosum of CX3CR1^−/− mice. Such patterns included disorganization or separation of their myelin sheath (K and L) and spheroid-like myelin-enclosed structures (M). Images were taken from mice sacrificed after 5 wk of cuprizone diet. One representative experiment out of two is shown. n = 3–6 mice/group. Bars: (A–D) 20 µm; (E–G) 5 µm; (H-M) 2 µm.