A LIGHT AND ELECTRON HISTOCHEMICAL APPROACH TO THE NODE OF RANVIER AND MYELIN OF PERIPHERAL NERVE FIBERS

The Hale staining reaction has been used to study the nature and distribution of acid mucopolysaccharides associated with mammalian peripheral myelinated nerve fibers. Histochemical blocking reactions were employed to determine the specificity of the method. Electron micrographs of parallel preparations were examined to discover the fine structural localization of the optically visible Prussian blue pigment. The observations reported suggest that there is a specific localization of a sulfated mucopolysaccharide in the region immediately surrounding the axolemma at the node of Ranvier. Other parts of the fiber, in particular the myelin sheath, show a preponderance of carboxyl groups. Attention is drawn to the variation in the form and distribution of the Hale stain product after differing fixation procedures. The effect of osmium tetroxide on ferrocyanide-treated material is examined and discussed. Attention is directed to possible physiologic implications of the presence of material with the known ion exchange properties of a sulfated mucopolysaccharide in the immediate environment of the ionically active nodal axon membrane.