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.
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.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
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).
Causey, G., andA. A. Barton: The cellular content of the endoneurium of peripheral nerve. Brain82, 594–598 (1959).
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).
Duncan, D.: A relation between axone diameter and myelination determined by measurement of myelinated spinal root fibres. J. comp. Neurol.60, 437–471 (1934).
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).
Espir, M. L. E., andD. T. C. Harding: Apparatus for measuring and counting myelinated nerve fibres. J. Neurol. Neurosurg. Psychiat.24, 287–290 (1961).
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).
——: Myelin formation in the sciatic nerve of the rat. J. Neuropath. exp. Neurol.27, 546 to 570 (1968).
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).
—: Further electron microscope studies of human foetal peripheral nerves. J. Anat. (Lond.)100, 487–502 (1966).
— andRosemary, A. Eames: An electron microscope study of the connective tissues of human peripheral nerve. J. Anat. (Lond.)98, 655–663 (1964).
Gasser, H. S.: Cold Spr. Harb. Symp. quant. Biol.17, 32–36 (1952).
—: Properties of dorsal root unmedullated fibres on the two sides of the ganglion. J. gen. Physiol.38, 709–728 (1955).
Hess, A.: The fine structure and morphological organization of non-myelinated nerve fibres. Proc. roy. Soc.144, 496–506 (1956).
Hiscoe, Helen B.: Distribution of nodes and incisures in normal and regenerated nerve fibres. Anat. Rec.99, 447–475 (1947).
Key, A., andG. Retzius: Studien in der Anatomie des Nervensystems und des Bindegewebes. Stockholm: Samson and Wallin 1876.
Landon, D. N., andP. L. Williams: Ultrastructure of the node of Ranvier. Nature (Lond.)199, 575–577 (1963).
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).
Lovarack, J. O., S. Sunderland, andL. J. Ray: The branching of nerve fibres in human cutaneous nerves. J. comp. Neurol.94, 293–311 (1951).
Nageotte, J.: L'Organisation de la matière dans ses raports avec la vie. Paris: F. Alcan 1922.
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).
Ochoa, J., andW. G. P. Mair: In preparation.
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).
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).
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).
Ranson, S. W.: Non-medullated nerve fibres in the spinal nerves. Amer. J. Anat.12, 67–87 (1911).
—: Unmyelinated nerve fibres as conductors of protopathic sensation. Brain38, 381–389 (1915).
—, andHelen, K. Davenport: Sensory unmyelinated fibres in the spinal nerves. Amer. J. Anat.48, 331–353 (1931).
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).
Remak: Obervationes anatomicae et microscopicae de systematis nervosi structura. Berlin 1838. Quoted byI. L. Tuckett.
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).
Sunderland, S., J. O. Lovarack, andL. J. Ray: The caliber of nerve fibres in human cutaneous nerves. J. comp. Neurol.91, 87–101 (1949).
Thomas, P. K.: The connective tissue of peripheral nerve: an electron microscope study. J. Anat. (Lond.)97, 35–44 (1963).
Thomas, P. K.: Personal communication.
—, andJean Slatford: Lamellar bodies in the cytoplasm of Schwann cells. J. Anat. (Lond.)98, 691 (1964).
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).
Tuckett, I. L.: On the structure and degeneration of non-medullated nerve fibres. J. Physiol. (Lond.)19, 267–311 (1896).
Vizoso, A. D.: The relationship between internodal length and growth in human nerves. J. Anat. (Lond.)84, 342–353 (1950).
Weller, R. O.: An electron microscopic study of hypertrophic neuropathy of Dejerine and Sottas. J. Neurol. Neurosurg. Psychiat.30, 111–125 (1967).
Williams, P. L., andD. N. Landon: Paranodal apparatus of peripheral myelinated nerve fibres of mammals. Nature (Lond.)198, 670–673 (1963).
Author information
Authors and Affiliations
Additional information
Read to the Queen Square Research Society, November 6th, 1967.
British Council Scholar on leave of absence from Escuela de Medicina, Universidad Austral, Valdivia, Chile.
Rights and permissions
About this article
Cite this article
Ochoa, J., Mair, W.G.P. The normal sural nerve in man. Acta Neuropathol 13, 197–216 (1969). https://doi.org/10.1007/BF00690642
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00690642