Impaired myelination in the central nervous system of NCmahTg mice. EM imaging of myelination in cross-sections of the corpus callosum of 1.5-year-old mice revealed the presence of thinly myelinated or unmyelinated large axons. A–C, control (wild-type or Cre-positive (no Cmah transgene)); D–F, NCmahTg. Scale bar = 1 μm. Data are representative of the results obtained from five mice per genotype in two independent experiments.