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Axonal projections of Renshaw cells in the thoracic spinal cord

Renshaw cells are widely distributed in all segments of the spinal cord, but detailed morphological studies of these cells and their axonal branching patterns have only been made for lumbosacral segments. For these, a characteristic distribution of terminals was reported, including extensive collate...

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Autores principales: Saywell, Shane A, Ford, Timothy W, Kirkwood, Peter A
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Blackwell Publishing Ltd 2013
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3871475/
https://www.ncbi.nlm.nih.gov/pubmed/24400162
http://dx.doi.org/10.1002/phy2.161
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author Saywell, Shane A
Ford, Timothy W
Kirkwood, Peter A
author_facet Saywell, Shane A
Ford, Timothy W
Kirkwood, Peter A
author_sort Saywell, Shane A
collection PubMed
description Renshaw cells are widely distributed in all segments of the spinal cord, but detailed morphological studies of these cells and their axonal branching patterns have only been made for lumbosacral segments. For these, a characteristic distribution of terminals was reported, including extensive collateralization within 1–2 mm of the soma, but then more restricted collaterals given off at intervals from the funicular axon. Previous authors have suggested that the projections close to the soma serve inhibition of motoneurons (known to be greatest for the motor nuclei providing the Renshaw cell excitation) but that the distant projections serve mainly the inhibition of other neurons. However, in thoracic segments, inhibition of motoneurons is known to occur over two to three segments (20–40 mm) from the presumed somatic locations of the Renshaw cells. Here, we report the first detailed morphological study of Renshaw cell axons outside the lumbosacral segments, which investigated whether this different distribution of motoneuron inhibition is reflected in a different pattern of Renshaw cell terminations. Four Renshaw cells in T7 or T8 segments were intracellularly labeled with neurobiotin in anesthetized cats and their axons traced for distances ≥6 mm from the somata. The only morphological difference detected within this distance in comparison with Renshaw cells in the lumbosacral cord was a minimal taper in the funicular axons, where in the lumbosacral cord this is pronounced. Patterns of termination were virtually identical to those in the lumbosacral segments, so we conclude that these patterns are unrelated to the pattern of motoneuronal inhibition.
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spelling pubmed-38714752014-01-07 Axonal projections of Renshaw cells in the thoracic spinal cord Saywell, Shane A Ford, Timothy W Kirkwood, Peter A Physiol Rep Original Research Renshaw cells are widely distributed in all segments of the spinal cord, but detailed morphological studies of these cells and their axonal branching patterns have only been made for lumbosacral segments. For these, a characteristic distribution of terminals was reported, including extensive collateralization within 1–2 mm of the soma, but then more restricted collaterals given off at intervals from the funicular axon. Previous authors have suggested that the projections close to the soma serve inhibition of motoneurons (known to be greatest for the motor nuclei providing the Renshaw cell excitation) but that the distant projections serve mainly the inhibition of other neurons. However, in thoracic segments, inhibition of motoneurons is known to occur over two to three segments (20–40 mm) from the presumed somatic locations of the Renshaw cells. Here, we report the first detailed morphological study of Renshaw cell axons outside the lumbosacral segments, which investigated whether this different distribution of motoneuron inhibition is reflected in a different pattern of Renshaw cell terminations. Four Renshaw cells in T7 or T8 segments were intracellularly labeled with neurobiotin in anesthetized cats and their axons traced for distances ≥6 mm from the somata. The only morphological difference detected within this distance in comparison with Renshaw cells in the lumbosacral cord was a minimal taper in the funicular axons, where in the lumbosacral cord this is pronounced. Patterns of termination were virtually identical to those in the lumbosacral segments, so we conclude that these patterns are unrelated to the pattern of motoneuronal inhibition. Blackwell Publishing Ltd 2013-11 2013-11-24 /pmc/articles/PMC3871475/ /pubmed/24400162 http://dx.doi.org/10.1002/phy2.161 Text en © 2013 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society http://creativecommons.org/licenses/by/2.5/ Re-use of this article is permitted in accordance with the Creative Commons Deed, Attribution 2.5, which does not permit commercial exploitation.
spellingShingle Original Research
Saywell, Shane A
Ford, Timothy W
Kirkwood, Peter A
Axonal projections of Renshaw cells in the thoracic spinal cord
title Axonal projections of Renshaw cells in the thoracic spinal cord
title_full Axonal projections of Renshaw cells in the thoracic spinal cord
title_fullStr Axonal projections of Renshaw cells in the thoracic spinal cord
title_full_unstemmed Axonal projections of Renshaw cells in the thoracic spinal cord
title_short Axonal projections of Renshaw cells in the thoracic spinal cord
title_sort axonal projections of renshaw cells in the thoracic spinal cord
topic Original Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3871475/
https://www.ncbi.nlm.nih.gov/pubmed/24400162
http://dx.doi.org/10.1002/phy2.161
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