Pronounced hypomyelination in J20.SK2Δ mice. A–L, Immunofluorescence for MBP (green) and NF-H (red) in the cortex (A–D), hippocampus (E–H), and cerebellum (I–L) of 13-month-old WT (A, E, I), SK2Δ (B, F, J), J20 (C, G, K), and J20.SK2Δ mice (D, H, L). M–P, MBP immunofluorescence in the hippocampus of 7-month-old WT (M), SK2Δ (N), J20 (O), or J20.SK2Δ mice (P). Scale bar, 200 μm.