Slide 15 Higher magnification of longitudinally cut nerve, showing a clear node of Ranvier in the center of the field. Note that the axon is continuous through the node. The lipid portion of the membranes has been dissolved out during tissue fixation. Slide 16 Detail of node of Ranvier, with axon continuing through it. Axons stain deep pink.
Myelin is pale because the lipid material disolves out.
An extension of cell cytoplasm wraps around the axon, making a multi-layered myelin sheath. Ordinarily there is one oligodendrocyte between two successive nodes of Ranvier. Notice that the cell has other cytoplasmic extensions up above, which are free to as sociate with other axons. One difference, however, is that a Schwann cell is believed to wrap only one axon instead of several. Slide 18 EM of myelinated axons of peripheral nerve.