Encyclopedia of Neuroscience

2009 Edition
| Editors: Marc D. Binder, Nobutaka Hirokawa, Uwe Windhorst

Axonal Sprouting in Health and Disease

  • Siu Lin Tam
  • Tessa Gordon
Reference work entry
DOI: https://doi.org/10.1007/978-3-540-29678-2_527


 Axonal sprouting is a process where fine nerve processes – sprouts – grow out from the intact axons to reinnervate denervated muscle fibers. Thereby the sprouting sustains the nerve supply to muscles and, in turn, the ability to move.


Axon sprouting from intact  motor units (a  motoneuron and the muscle fibers that it supplies) commonly compensates for motoneuron loss in aging and/or in diseases such as poliomyelitis and amyotrophic lateral sclerosis, and/or partial nerve injuries due to the loss of axonal contact and/or death of many of the motoneurons [1]. The Schwann cells at the neuromuscular junction, the  perisynaptic Schwann cells, play an essential role in leading the axon sprouts from intact axons to the denervated muscle fibers to reinnervate them at the neuromuscular junction. Excessive neuromuscular activity interferes with the normal role of the perisynaptic Schwann cells and thereby the enlargement of motor units (the inclusion of more muscle...

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  1. 1.
    Gordon T, Hegedus J, Tam SL (2004) Adaptive and maladaptive motor axonal sprouting in aging and motoneuron disease. Neurol Res 26:174–185PubMedGoogle Scholar
  2. 2.
    Rafuse VF, Gordon T (1996) Self-reinnervated cat medial gastrocnemius muscles. I. Comparisons of the capacity of regenerating nerves to form enlarged motor units after extensive peripheral nerve injuries. J Neurophysiol 75:268–281PubMedGoogle Scholar
  3. 3.
    Tam SL, Gordon T (2003) Neuromuscular activity impairs axonal sprouting in partially denervated muscles by inhibiting bridge formation of perisynaptic Schwann cells. J. Neurobiol 57:221–234PubMedGoogle Scholar
  4. 4.
    Georgiou J, Robitaille R, Charlton MP (1999) Muscarinic control of cytoskeleton in perisynaptic glia. J Neurosci 19:3836–3846PubMedGoogle Scholar
  5. 5.
    Tam SL, Archibald V, Jassar B, Tyreman N, Gordon T (2001) Increased neuromuscular activity reduces sprouting in partially denervated muscles. J Neurosci 21:654–667PubMedGoogle Scholar
  6. 6.
    Tam SL, Archibald V, Tyreman N, Gordon T (2002) Tetrodotoxin prevents motor unit enlargement after partial denervation. J Physiol 543:655–663PubMedGoogle Scholar
  7. 7.
    Connold AL, Vrbova G (1991) Temporary loss of activity prevents the increase of motor unit size in partially denervated rat soleus muscles. J Physiol 434:107–119PubMedGoogle Scholar
  8. 8.
    McComas AJ (2001) Skeletal muscle. Human Kinetics, Champaign, ILGoogle Scholar
  9. 9.
    Tam SL, Archibald V, Tyreman N, Gordon T (2002) Effect of exercise on stability of chronically enlarged motor units. Muscle Nerve 25: 359–369PubMedGoogle Scholar
  10. 10.
    Frey D, Schneider C, Xu L, Borg J, Spooren W, Caroni P (2000) Early and selective loss of neuromuscular synapse subtypes with low sprouting competence in motoneuron diseases. J Neurosci 20:2534–2542PubMedGoogle Scholar

Copyright information

© Springer-Verlag GmbH Berlin Heidelberg 2008

Authors and Affiliations

  • Siu Lin Tam
    • 1
  • Tessa Gordon
    • 1
  1. 1.Centre of Neuroscience, Division of Physical Medicine and Rehabilitation, Faculty of Medicine and DentistryUniversity of AlbertaEdmontonCanada