Dnβ1 oligodendrocytes myelinate a reduced number of internodes in myelinating co-cultures. (a) Representative pictures are shown for wild-type, dnβ1, and dnβ3 MBP⁺ oligodendrocytes myelinating neurites within DRG neuron cultures at low (top panels) and high (bottom panels) magnification. Bars: top, 133 µm; bottom, 50 µm. (b) (left) Neurosphere-derived dnβ1 oligodendrocytes myelinate DRG neurons less efficiently than their wild-type or dnβ3 counterparts. Error bars represent SD (**, P < 0.01). The internodal number (middle) and length (right) were quantified for each oligodendrocyte (10 oligodendrocytes per experiment, n = 5). Dnβ1 oligodendrocytes showed a decrease in the internodal number per oligodendrocyte (*, P < 0.05), whereas the internodal length was unchanged for the three genotypes.