Nodes of Ranvier are found to occur along a myelinated axon of the neuron. It is also called as myelin-sheath gaps. The axolemma or the membrane at the node is exposed to the extracellular space. These gaps are not insulated and highly enriched in ion channels. The nodal area participates in the exchange of ions which is necessary for regeneration of the action potential.

Non-medullated axons are without myelin sheath.

Schwann cells, a type of glial cells, help in keeping the peripheral nerve fibres alive. It is found in both myelinated and non-myelinated axons. Schwann cells form the myelin sheath in the myelinated axon.