Acta Neuropathologica

, Volume 13, Issue 3, pp 197–216 | Cite as

The normal sural nerve in man

I. Ultrastructure and numbers of fibres and cells
  • José Ochoa
  • W. G. P. Mair
Original Investigations

Summary

A combined light and electron microscope study of the normal sural nerve in 7 people aged 15–59 years is reported. Qualitative and quantitative studies of the Schwann cells and fibroblasts, myelinated and unmyelinated fibres are made in isolated fascicles.

Schwann cells predominate over fibroblasts in the ratio of about 9-1. Most Schwann cells, almost 80%, are attached to unmyelinated fibres. Factors influencing the densities of these cells per cross sectional area are discussed.

Some ultrastructural features of the myelinated fibres are described and their numbers per sq.mm and frequency distribution of their sizes are produced. An indirect method is proposed for assessing the mean internodal length for earch of the myelinated fibre size populations in cross sections of fascicles of normal nerves by estimating the proportion of myelinated segments cut through their nucleus.

The ultrastructure of unmyelinated fibres is described and the identification of axons of extreme diameter is discussed. Their densities and size frequency histograms are the first to be reported in man by systematic electron microscope studies. The average ratio of unmyelinated to myelinated fibre density is about 3.7:1 though it varies in the fascicles of the different individuals.

The implications of axonal diameter in the presence of myelin are commented on.

Key-Words

Peripheral Nerves Axons Myelin Sheaths Schwann Cells Electron Microscopy 

Zusammenfassung

Eine kombinierte licht- und elektronenmikroskopische Untersuchung am normalen N. suralis von 7 Menschen im Alter von 15–59 Jahren wurde vorgenommen. Qualitative und quantitative Beobachtungen an Schwann-Zellen und Fibroblasten, markhaltigen und marklosen Fasern wurden an isolierten Faszikeln durchgeführt.

Schwannzellen überwiegen gegenüber Fibroblasten im Verhältnis von etwa 9:1. Die meisten Schwannzellen (etwa 80%) liegen an marklosen Fasern. Die Faktoren, welche die Dichte dieser Zellen pro Querschnittsareal beeinflußen, werden diskutiert.

Einige ultrastrukturelle Befunde an bemarkten Fasern werden beschrieben und ihre Zahl pro mm2 sowie die Häufigkeitsverteilung ihrer Dicke wird angegeben. Eine indirekte Methode zur Bestimmung der mittleren Internodienlänge für jede der Markfasergrößenpopulationen an Querschnitten von Faszikeln normaler Nerven durch Bestimmung des Verhältnisses der markhaltigen Fasersegmente zu ihrer Kernzahl wird vorgeschlagen.

Die Ultrastruktur der marklosen Nervenfaern wird beschrieben und die Identifizierung dieser Axone mit extremen Durchmessern diskutiert. Ihre Dichte und Größenfrequenzhistogramme sind die ersten, die am Menschen durch systematische elektronenoptische Untersuchungen veröffentlicht werden. Das mittlere Verhältnis von marklosen zu bemarkten Fasern ist etwa 3,7:1 und schwankt in den Faszikeln der Einzelindividuen.

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References

  1. Boycott, A. E.: On the number of nodes of Ranvier in different stages of the growth of nerve fibres in the frog. J. Physiol. (Lond.)30, 370–380 (1904).Google Scholar
  2. Causey, G., andA. A. Barton: The cellular content of the endoneurium of peripheral nerve. Brain82, 594–598 (1959).Google Scholar
  3. Cravioto, H.: The role of Schwann cells in the development of human peripheral nerves. An electron microscopic study. J. Ultrastruct. Res.12, 634–651 (1965).Google Scholar
  4. Duncan, D.: A relation between axone diameter and myelination determined by measurement of myelinated spinal root fibres. J. comp. Neurol.60, 437–471 (1934).Google Scholar
  5. Dyck, P. J., andE. H. Lambert: Numbers and diameters of nerve fibres and compound action potential of sural nerve: controls and hereditary neuromuscular disorders. Trans. Amer. Neurol. Ass.91, 214–217 (1966).Google Scholar
  6. Espir, M. L. E., andD. T. C. Harding: Apparatus for measuring and counting myelinated nerve fibres. J. Neurol. Neurosurg. Psychiat.24, 287–290 (1961).Google Scholar
  7. Friede, R. L., andT. Samorajski: Relation between the number of myelin lamellae and axon circumference in fibres of vagus and sciatic nerves of mice. J. comp. Neurol.130, 223–232 (1967).Google Scholar
  8. ——: Myelin formation in the sciatic nerve of the rat. J. Neuropath. exp. Neurol.27, 546 to 570 (1968).Google Scholar
  9. Gamble, H. J.: Comparative electron-microscopic observations on the connective tissues of a peripheral nerve and a peripheral root in the rat. J. Anat. (Lond.)98, 17–25 (1964).Google Scholar
  10. —: Further electron microscope studies of human foetal peripheral nerves. J. Anat. (Lond.)100, 487–502 (1966).Google Scholar
  11. — andRosemary, A. Eames: An electron microscope study of the connective tissues of human peripheral nerve. J. Anat. (Lond.)98, 655–663 (1964).Google Scholar
  12. Gasser, H. S.: Cold Spr. Harb. Symp. quant. Biol.17, 32–36 (1952).Google Scholar
  13. —: Properties of dorsal root unmedullated fibres on the two sides of the ganglion. J. gen. Physiol.38, 709–728 (1955).Google Scholar
  14. Hess, A.: The fine structure and morphological organization of non-myelinated nerve fibres. Proc. roy. Soc.144, 496–506 (1956).Google Scholar
  15. Hiscoe, Helen B.: Distribution of nodes and incisures in normal and regenerated nerve fibres. Anat. Rec.99, 447–475 (1947).Google Scholar
  16. Key, A., andG. Retzius: Studien in der Anatomie des Nervensystems und des Bindegewebes. Stockholm: Samson and Wallin 1876.Google Scholar
  17. Landon, D. N., andP. L. Williams: Ultrastructure of the node of Ranvier. Nature (Lond.)199, 575–577 (1963).Google Scholar
  18. Lascelles, R. G., andP. K. Thomas: Changes due to age in internodal length in the sural nerve in man. J. Neurol. Neurosurg. Psychiat.29, 40–44 (1966).Google Scholar
  19. Lovarack, J. O., S. Sunderland, andL. J. Ray: The branching of nerve fibres in human cutaneous nerves. J. comp. Neurol.94, 293–311 (1951).Google Scholar
  20. Nageotte, J.: L'Organisation de la matière dans ses raports avec la vie. Paris: F. Alcan 1922.Google Scholar
  21. Ochoa, J., andJ. D. Vial: Behaviour of the peripheral nerve structures in chronic neuropathies with special reference to the Schwann cell. J. Anat. (Lond.)102, 95–111 (1967).Google Scholar
  22. Ochoa, J., andW. G. P. Mair: In preparation.Google Scholar
  23. O'Sullivan, D. J., andM. Swallow: The fibre size and content of the radial and sural nerves. J. Neurol. Neurosurg. Psychiat.31, 464–470 (1968).Google Scholar
  24. Paintal, A. S.: A comparison of the nerve impulses of mammalian non-medullated nerve fibres with those of the smallest diameter medullated fibres. J. Physiol. (Lond.)193, 523–533 (1967).Google Scholar
  25. Peters, A., andA. R. Muir: The relationship between axons and Schwann cells during development of peripheral nerves in the rat. Quart. J. exp. Physiol.44, 117–130 (1959).Google Scholar
  26. Ranson, S. W.: Non-medullated nerve fibres in the spinal nerves. Amer. J. Anat.12, 67–87 (1911).Google Scholar
  27. —: Unmyelinated nerve fibres as conductors of protopathic sensation. Brain38, 381–389 (1915).Google Scholar
  28. —, andHelen, K. Davenport: Sensory unmyelinated fibres in the spinal nerves. Amer. J. Anat.48, 331–353 (1931).Google Scholar
  29. Ranson, S. W., W. H. Droegenmueller, H. K. Davenport, andC. Fisher: Number, size and myelination of the sensory fibres in the cerebrospinal nerves. In Sensation, its mechanisms and disturbances. Ass. Res. nerv. Dis. Proc.15, 3–34 (1935).Google Scholar
  30. Remak: Obervationes anatomicae et microscopicae de systematis nervosi structura. Berlin 1838. Quoted byI. L. Tuckett.Google Scholar
  31. Reynolds, E. S.: The use of lead citrate at high pH as an electron-opaque stain in electron microscopy. J. Cell Biol.17, 208–212 (1963).Google Scholar
  32. Sunderland, S., J. O. Lovarack, andL. J. Ray: The caliber of nerve fibres in human cutaneous nerves. J. comp. Neurol.91, 87–101 (1949).Google Scholar
  33. Thomas, P. K.: The connective tissue of peripheral nerve: an electron microscope study. J. Anat. (Lond.)97, 35–44 (1963).Google Scholar
  34. Thomas, P. K.: Personal communication.Google Scholar
  35. —, andJean Slatford: Lamellar bodies in the cytoplasm of Schwann cells. J. Anat. (Lond.)98, 691 (1964).Google Scholar
  36. Trump, B. F., E. A. Smuckler, andE. P. Bendit: A method for staining epoxy sections for light microscopy. J. Ultrastruct. Res.5, 343–348 (1961).Google Scholar
  37. Tuckett, I. L.: On the structure and degeneration of non-medullated nerve fibres. J. Physiol. (Lond.)19, 267–311 (1896).Google Scholar
  38. Vizoso, A. D.: The relationship between internodal length and growth in human nerves. J. Anat. (Lond.)84, 342–353 (1950).Google Scholar
  39. Weller, R. O.: An electron microscopic study of hypertrophic neuropathy of Dejerine and Sottas. J. Neurol. Neurosurg. Psychiat.30, 111–125 (1967).Google Scholar
  40. Williams, P. L., andD. N. Landon: Paranodal apparatus of peripheral myelinated nerve fibres of mammals. Nature (Lond.)198, 670–673 (1963).Google Scholar

Copyright information

© Springer-Verlag 1969

Authors and Affiliations

  • José Ochoa
    • 1
  • W. G. P. Mair
    • 1
  1. 1.Institute of NeurologyThe National HospitalLondonEngland

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