Quantitative relationships between axoplasm and Schwann cell sheath in unmyelinated nerve fibres: an electron microscope study

The quantitative relationships between the size of the Schwann cell sheath and that of its related axoplasm were studied by electron microscopy in cross sections of bundles of unmyelinated axons (Remak bundles) of the spinal roots of lizard (Lacerta muralis). It was found that (i) the cross sectiona...

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Bibliographic Details
Published in:Journal of anatomy 1988-08, Vol.159, p.49-56
Main Authors: PANNESE, E, ARCIDIACONO, G, FRATTOLA, D, RIGAMONTI, L, PROCACCI, P, LEDDA, M
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Cell Membrane - ultrastructure
Cytoplasm - ultrastructure
Fundamental and applied biological sciences. Psychology
Isolated neuron and nerve. Neuroglia
Lizards
Microscopy, Electron
Nerve Fibers - ultrastructure
Schwann Cells - ultrastructure
Spinal Nerve Roots - ultrastructure
Vertebrates: nervous system and sense organs
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Summary:The quantitative relationships between the size of the Schwann cell sheath and that of its related axoplasm were studied by electron microscopy in cross sections of bundles of unmyelinated axons (Remak bundles) of the spinal roots of lizard (Lacerta muralis). It was found that (i) the cross sectional area of the Schwann cell sheath is directly proportional to that of its related axoplasm (correlation coefficient 0.84), and (ii) the ratio between the cross sectional area of the Schwann cell sheath and that of its related axoplasm tends to diminish as the cross sectional area of the latter increases. Thus, under normal conditions, in the bundles of unmyelinated axons of the spinal roots of lizard a quantitative balance exists between the nerve tissue and its associated glial tissue. These results agree with those previously obtained in the myelinated fibres of the same region and in the spinal ganglia of the lizard, gecko, cat and rabbit. Some of the mechanisms probably involved in the control of the quantitative balance between nerve tissue and its associated glial tissue in peripheral nerves are listed.
ISSN:0021-8782
1469-7580