An example of PNS myelinated nerve fiber is shown. (B) Illustration of transverse section of myelinated axon at the internode ... expressed in myelin. Nodes of Ranvier (arrows) are stained ...

In contrast, among the myelinated nerve fibers, axons are mostly covered by myelin sheaths, and transmembrane currents can only occur at the nodes of Ranvier where the axonal membrane is exposed.