In the PNS, one Schwann cell forms a single myelin sheath (Figure 1A). By contrast, in the CNS, the oligodendrocyte sends cell processes to myelinate multiple segments on many axons (Figure 2).

This illustration shows the proposed role of myelinophagy in a Schwann cell after nerve injury and axon degeneration (right). The myelin sheath breaks up into fragments in the cytoplasm that are ...