Sometimes called fibers of Remak. There is no medullary or myelin sheath Axis cylinder is very slender and the thin neurolemma sheath contains scattered nuclei of Schwann cells.
There are no nodes of Ranvier, up to a dozen or more of these nerve fibres are enclosed by the cytoplasm of the same sheath of Schwann cells.
Majority of the axons of automatic ganglia and the processes of many of the smaller cerebrospinal ganglia have no myelin sheath.
In the CNS there are many non-myelinated nerve fibres (without neurolemma).
