Tags: Anatomical Structure.
In the peripheral nervous system (PNS) axons can be either myelinated or unmyelinated. Myelination means that the axon is insulated by surrounding layers of fatty membrane (myelin) produced by Schwann cells. These layers are continuous (like rolling up rope) but due to the way they are formed they often include small amounts of Schwann cell cytoplasm not displaced to the periphery during Schwann cell formation of the myelin.
