Acta Neuropathologica

, Volume 60, Issue 3–4, pp 291–296 | Cite as

Node-like axonal specialisations along demyelinated central nerve fibres: Ultrastructural observations

  • W. F. Blakemore
  • K. J. Smith
Original Works


Ultrastructural examination of long-term (1 month to 1 year) demyelinated axons of the central nervous system (CNS) has revealed the presence of certain features typical of nerve fibres at the node of Ranvier. Focal regions of dense undercoating of the axolemma were observed and these always extended along regions which were intimately associated with the processes of gial cells. In many cases the glial cells were astrocytes, but in some cases the cells resembled Schwann cells. The astrocytic and Schwann cell processes were sometimes finger-like and they thus resembled the normal projections of these cells onto the nodal axolemma of central and peripheral nerve fibres, respectively. Since the undercoated regions which were associated with astrocytic processes were also often remote from any oligodendrocyte or Schwann cell processes, it seems that certain node-like specialisations may form or be sustained in the absence of myelin-forming cells.

Key words

CNS Node of Ranvier Demyelination Astrocytes 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Berthold C-H (1978) Morphology of normal peripheral axons. In: Waxman SG (ed) Physiology and pathobiology of axons. Raven Press, New YorkGoogle Scholar
  2. Blakemore WF (1982) Ethidium bromide induced demyelination in the spinal cord of the cat. Neuropathol Appl Neurobiol 8:365–375Google Scholar
  3. Blakemore WF, Patterson RA (1978) Suppression of remyelination in the CNS by X-irradiation. Acta Neuropathol (Berl) 42: 105–113Google Scholar
  4. Blakemore WF, Eames RA, Smith KJ, McDonald WI (1977) Remyelination in the spinal cord of the cat following intraspinal injections of lysolecithin. J Neurol Sci 33:33–43Google Scholar
  5. Bostock H, Hall SM, Smith KJ (1980) Demyelinated axons can form “nodes” prior to remyelination. J Physiol 308:21P-23PGoogle Scholar
  6. Carlstedt T (1977) Observations on the morphology at the transition between the peripheral and the central nervous system in the cat. IV. Unmyelinated fibres in S, dorsal rootlets. Acta Physiol Scand [Suppl] 446:61–72Google Scholar
  7. Elfvin L-G (1961) The ultrastructure of the nodes of Ranvier in cat sympathetic nerve fibres. J Ultrastruct Res 5:374–387Google Scholar
  8. Hildebrand C, Waxman SG (1983) Regional node-like membrane specialisations in non-myelinated axons of rat retinal nerve fibre layer. Brain Res 258:23–32Google Scholar
  9. Ludwin SK (1980) Chronic demyelination inhibits remyelination in the central nervous system. Lab Invest 43:382–387Google Scholar
  10. Peters A (1966) The node of Ranvier in the central nervous system. Q J Exp Physiol 51:229–236Google Scholar
  11. Raine CS (1978) Membrane specialisations between demyelinated axons and astroglia in chronic EAE lesions and multiple sclerosis plaques. Nature 275:326–327Google Scholar
  12. Robertson JD (1959) Preliminary observations on the ultrastructure of nodes of Ranvier. Z Zellforsch 50:553–560Google Scholar
  13. Rosenbluth J (1979) Aberrant axon-Schwann cell junctions in dystrophic mouse nerves. J Neurocytol 8:655–672Google Scholar
  14. Smith KJ, Bostock H, Hall SM (1982) Saltatory conduction precedes remyelination in axons demyelinated with lysophosphatidyl choline. J Neurol Sci 54:13–31Google Scholar
  15. Waxman SG, Foster RE (1980) Ionic channel distribution and heterogeneity of the axon membrane in myelinated fibres. Brain Res Rev 2:205–234Google Scholar

Copyright information

© Springer-Verlag 1983

Authors and Affiliations

  • W. F. Blakemore
    • 1
  • K. J. Smith
    • 2
  1. 1.Dept. of Clinical Veterinary MedicineUniversity of CambridgeCambridgeEngland
  2. 2.Dept. of PhysiologyRush-Presbyterian-St. Luke's Medical CenterChicagoUSA

Personalised recommendations