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The amount of slow axonal transport is proportional to the radial dimensions of the axon

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Journal of Neurocytology

Summary

Axons are fundamentally cylindrical and their geometry is defined by two basic parameters, i.e. diameter and length. The average cross-sectional diameter of an axon is determined primarily by the number and density of cytoskeletal structures (i.e. microtubules and neurofilaments) in the axon. The proteins that constitute these structures are synthesized in the nerve cell body and are conveyed through the axon by slow axonal transport. In particular, slow component a (SCa) supplies all of the axonal neurofilament proteins and most of the microtubule proteins to the axon. To study the relationship between slow axonal transport and axonal diameter, the slowly transported proteins were radiolabelled in rat dorsal root ganglion (DRG) cells. The amount of radiolabelled SCa proteins transported in individual unmyelinated and myelinated DRG axons was measured by the electron microscopic autoradiographic method. We found that the amount of SCa transported in the axons is proportional to axonal cross-sectional area. These results indicate that slow axonal transport of microtubules and neurofilaments is a primary determinant of axonal diameter.

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Author notes

  1. Jerome R. Wujek

    Present address: Institute for Developmental Research, Children's Hospital Medical Center, 45229, Cincinnati, Ohio, USA

Authors and Affiliations

  1. Bio-architectonics Center, Case Western Reserve University, 44106, Cleveland, Ohio, USA

    Jerome R. Wujek & Raymond J. Lasek

  2. Division of Neuropathology-Department of Pathology, Case Western Reserve University, 44106, Cleveland, Ohio, USA

    Pierluigi Gambetti

Authors
  1. Jerome R. Wujek
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  2. Raymond J. Lasek
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  3. Pierluigi Gambetti
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Wujek, J.R., Lasek, R.J. & Gambetti, P. The amount of slow axonal transport is proportional to the radial dimensions of the axon. J Neurocytol 15, 75–83 (1986). https://doi.org/10.1007/BF02057906

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  • DOI: https://doi.org/10.1007/BF02057906

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