Although freeze fracture studies have revealed that the nodal axolemma in both the CNS and PNS is enriched in intra-membranous particles (IMPs) compared to the internode, there are some structural differences reflecting their cellular constituents.  In the PNS, specialized microvilli project from the outer collar of Schwann cells and come very close to nodal axolemma of large fibers.  The projections of the Schwann cells are perpendicular to the node and are radiating from the central axons.  However, in the CNS, one or more of the astrocytic processes come in close vicinity of the nodes.  Researchers declare that these processes stem from multi-functional astrocytes, as opposed to from a population of astrocytes dedicated to contacting the node.  On the other hand, in the PNS, the basal lamina that surrounds the Schwann cells is continuous across the node.