where are unmyelinated nerve fibers surrounded by schwann cells
Structure [edit]. Schwann cells are a variety of glial cell that keep peripheral nerve fibres (both myelinated and unmyelinated) alive. In myelinated axons, Schwann cells form the myelin sheath (see above). The sheath is not continuous.Individual myelinating Schwann cells cover about 100 micrometres of an axonâequating to approximately 10,000 Schwann cells along a 1 metre length of the axon.n this sense, Schwann cells are the peripheral nervous system's analogues of the central nervous system 's oligodendrocytes. However, unlike oligodendrocytes, each myelinating Schwann cell provides insulation to only one axon (see image).