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NODE OF RANVIER---MYELINATED NERVE FIBER in a NERVE, Longitudinal Section, 400X. Nodes of Ranvier appear as constrictions or narrow gaps in the MYELIN SHEATH that surrounds the nerve fiber (usually an axon) of a myelinated nerve fiber. In this image the nerve fiber that is associated with the Node of Ranvier has a deep red color. The Myelin Sheath is the clear space surrounding the nerve fiber and has a high amount of lipid that insulates the nerve fiber. The Nodes of Ranvier are uninsulated areas with many ion channels. Neurons that are myelinated and have nodes of Ranvier demonstrate SALTATORY ("jumping") -- Conduction of the nerve impulse (action potential), were the nerve impulse seems to Jump from node to node instead of the continuous conduction in unmyelinated nerve fibers. Myelinated nerve fibers have much faster nerve impulse conduction compared to unmyelinated nerve fibers. Axon diameter also affects the speed of nerve impulse conduction.