Localizations of ruthenium red positive material in rabbit peripheral nerves

The penetration and distribution of ruthenium red in the axon-myelin-Schwann cell complex of developing rabbit peripheral nerve fibers are investigated. Ruthenium red positive material is established in the axoplasm, axolemma, periaxonal space, major dense lines and intraperiod lines of the compact myelin, mesaxons, split peripheral myelin lamellae, Schmidt-Lanterman and longitudinal incisures, paranodal loops and axo-glial contacts, Schwann cell cytoplasm and basal lamina, nodal extracellular matrix, desmosome-like structures, endoneural collagen. Some features of the distribution of the contrast material in the developing myelin sheath are described. Regional differences of the axolemma and of the Schwann cell cytoplasm and plasmalemma are established. The prevalence of glycoproteins or glycolipids in the ruthenium red stained material in its different localizations is discussed on the basis of trypsin and hyaluronidase digestion performed.