Are Schwann cells the sole source of myelination in PNS?
Schwann cells seem to be the most common type of glial cells outside of CNS, and the myelinating Schwann cells are the only known source of myelin in PNS. Other types of neuroglia in PNS, for example non-myelinating Schwann cells and astrocytes-like cells do not seem to take part in myelination, neither in CNS nor in PNS.