Figure 2.

Compact myelin ultrastructure is normal in long-term netrin-1 and DCC mutant cerebellar slice cultures. Spacing between layers of the myelin sheath was analyzed by transmission electron microscopy in cross sections cut from cerebellar slice cultures derived from DCC^−/− or netrin-1^−/− animals (B, D, respectively) and their wild-type littermates (A, C, respectively). The width of the periaxonal space was unaffected in the mutant slices. Although the periodicity of netrin-1^+/+ and netrin-1^−/− myelin wraps was not significantly different, the absence of DCC expression resulted in a small (∼11%), but significant, increase in the spacing between layers of compact myelin (supplemental Table 1, available at www.jneurosci.org as supplemental material). Electron micrographs were imaged at 410,000×. Ax, Axon; PS, periaxonal space. Scale bar, 50 nm.