RTN4 and myeloid sarcoma: The increased proportion of ermin+ oligodendrocytes compared to Nogo-A+ cells in areas of remyelination may be due to an increased density of not fully mature oligodendrocytes, but it could also be partly due to a disproportionate loss of mature oligodendrocytes in these areas, as remyelination in MS and in CPZ occurs simultaneously with myelin and oligodendrocyte loss [10].