Lumbar motoneurons of man II: the number and diameter distribution of large and intermediate diameter cytons in 'motoneuron columns' of spinal cord of man

Y. Kawamura, P. O'Brien, H. Okazaki, Peter J Dyck

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Abstract

Using a methodology which corrects for split error, and for the linear relationship between diameter of nucleolus and of cell body (cyton) and using semi-automatic methods of counting and sizing and programmed calculation and plotting, the number and diameter histograms of cytons of L-3, L-4, and L-5 motoneuron columns of 18 reference spinal cords of man (ages 17 to 82 years) have been evaluated. The number and frequency distribution of diameters (diameter histograms) of myelinated fibers of L-3, L-4 and L-5 ventral spinal roots (VSRs) had been determined in a preceding study as a control to validate the estimated number of alpha and gamma motoneuron cytons determined in this study from the same segment of spinal cord. The diameter histograms of cytons of motoneuron columns consistently contain three discrete peaks: a large-diameter peak (CL), an intermediate-diameter (CI) and small-diameter peak (CS). To illustrate, on the average, there were 4874 ± 585 large cytons and 1700 ± 564 ← intermediate cytons in the L5 segment of spinal cord. A reasonably close concordance was found between the average number of large cytons of spinal cord segments and the number of large-diameter myelinated fibers of ventral spinal roots (VSRs) (0.91, 0.94, and 0.98 for L3, L4 and L5 spinal cord segments and ventral spinal roots, respectively). For the ratio of the number of intermediate cytons to the number of intermediate axons the concordance was not as good (0.77, 0.85, and 1.14 for L3, L4 and L5 segments, respectively). Assuming that a cyton provides only one axon to VSR it is reasonable to infer from the studies that most large-diameter cytons are those of alpha motoneurons and that most of the intermediate-diameter cytons are those of gamma motor neurons. The greater number of axons than of cytons for the intermediate diameter group may be from a spurious inclusion of small-diameter axons (possibly pre-ganglionic autonomic fibers) with the intermediate-diameter group. On the average, the range of diameters of large-diameter cyton population in motoneuron columns was found to be 33 to 59 μm and for intermediate-diameter cytons was 24 to 33 μm. The total number of cytons per L3, L4 and L5 segments fell at a rate of ∞260, 175 and 200 per decade, respectively.

Original languageEnglish (US)
Pages (from-to)861-870
Number of pages10
JournalJournal of Neuropathology and Experimental Neurology
Volume36
Issue number5
StatePublished - 1977

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Spinal Nerve Roots
Motor Neurons
Spinal Cord
Axons
Gamma Motor Neurons

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Neuroscience(all)

Cite this

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title = "Lumbar motoneurons of man II: the number and diameter distribution of large and intermediate diameter cytons in 'motoneuron columns' of spinal cord of man",
abstract = "Using a methodology which corrects for split error, and for the linear relationship between diameter of nucleolus and of cell body (cyton) and using semi-automatic methods of counting and sizing and programmed calculation and plotting, the number and diameter histograms of cytons of L-3, L-4, and L-5 motoneuron columns of 18 reference spinal cords of man (ages 17 to 82 years) have been evaluated. The number and frequency distribution of diameters (diameter histograms) of myelinated fibers of L-3, L-4 and L-5 ventral spinal roots (VSRs) had been determined in a preceding study as a control to validate the estimated number of alpha and gamma motoneuron cytons determined in this study from the same segment of spinal cord. The diameter histograms of cytons of motoneuron columns consistently contain three discrete peaks: a large-diameter peak (CL), an intermediate-diameter (CI) and small-diameter peak (CS). To illustrate, on the average, there were 4874 ± 585 large cytons and 1700 ± 564 ← intermediate cytons in the L5 segment of spinal cord. A reasonably close concordance was found between the average number of large cytons of spinal cord segments and the number of large-diameter myelinated fibers of ventral spinal roots (VSRs) (0.91, 0.94, and 0.98 for L3, L4 and L5 spinal cord segments and ventral spinal roots, respectively). For the ratio of the number of intermediate cytons to the number of intermediate axons the concordance was not as good (0.77, 0.85, and 1.14 for L3, L4 and L5 segments, respectively). Assuming that a cyton provides only one axon to VSR it is reasonable to infer from the studies that most large-diameter cytons are those of alpha motoneurons and that most of the intermediate-diameter cytons are those of gamma motor neurons. The greater number of axons than of cytons for the intermediate diameter group may be from a spurious inclusion of small-diameter axons (possibly pre-ganglionic autonomic fibers) with the intermediate-diameter group. On the average, the range of diameters of large-diameter cyton population in motoneuron columns was found to be 33 to 59 μm and for intermediate-diameter cytons was 24 to 33 μm. The total number of cytons per L3, L4 and L5 segments fell at a rate of ∞260, 175 and 200 per decade, respectively.",
author = "Y. Kawamura and P. O'Brien and H. Okazaki and Dyck, {Peter J}",
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T1 - Lumbar motoneurons of man II

T2 - the number and diameter distribution of large and intermediate diameter cytons in 'motoneuron columns' of spinal cord of man

AU - Kawamura, Y.

AU - O'Brien, P.

AU - Okazaki, H.

AU - Dyck, Peter J

PY - 1977

Y1 - 1977

N2 - Using a methodology which corrects for split error, and for the linear relationship between diameter of nucleolus and of cell body (cyton) and using semi-automatic methods of counting and sizing and programmed calculation and plotting, the number and diameter histograms of cytons of L-3, L-4, and L-5 motoneuron columns of 18 reference spinal cords of man (ages 17 to 82 years) have been evaluated. The number and frequency distribution of diameters (diameter histograms) of myelinated fibers of L-3, L-4 and L-5 ventral spinal roots (VSRs) had been determined in a preceding study as a control to validate the estimated number of alpha and gamma motoneuron cytons determined in this study from the same segment of spinal cord. The diameter histograms of cytons of motoneuron columns consistently contain three discrete peaks: a large-diameter peak (CL), an intermediate-diameter (CI) and small-diameter peak (CS). To illustrate, on the average, there were 4874 ± 585 large cytons and 1700 ± 564 ← intermediate cytons in the L5 segment of spinal cord. A reasonably close concordance was found between the average number of large cytons of spinal cord segments and the number of large-diameter myelinated fibers of ventral spinal roots (VSRs) (0.91, 0.94, and 0.98 for L3, L4 and L5 spinal cord segments and ventral spinal roots, respectively). For the ratio of the number of intermediate cytons to the number of intermediate axons the concordance was not as good (0.77, 0.85, and 1.14 for L3, L4 and L5 segments, respectively). Assuming that a cyton provides only one axon to VSR it is reasonable to infer from the studies that most large-diameter cytons are those of alpha motoneurons and that most of the intermediate-diameter cytons are those of gamma motor neurons. The greater number of axons than of cytons for the intermediate diameter group may be from a spurious inclusion of small-diameter axons (possibly pre-ganglionic autonomic fibers) with the intermediate-diameter group. On the average, the range of diameters of large-diameter cyton population in motoneuron columns was found to be 33 to 59 μm and for intermediate-diameter cytons was 24 to 33 μm. The total number of cytons per L3, L4 and L5 segments fell at a rate of ∞260, 175 and 200 per decade, respectively.

AB - Using a methodology which corrects for split error, and for the linear relationship between diameter of nucleolus and of cell body (cyton) and using semi-automatic methods of counting and sizing and programmed calculation and plotting, the number and diameter histograms of cytons of L-3, L-4, and L-5 motoneuron columns of 18 reference spinal cords of man (ages 17 to 82 years) have been evaluated. The number and frequency distribution of diameters (diameter histograms) of myelinated fibers of L-3, L-4 and L-5 ventral spinal roots (VSRs) had been determined in a preceding study as a control to validate the estimated number of alpha and gamma motoneuron cytons determined in this study from the same segment of spinal cord. The diameter histograms of cytons of motoneuron columns consistently contain three discrete peaks: a large-diameter peak (CL), an intermediate-diameter (CI) and small-diameter peak (CS). To illustrate, on the average, there were 4874 ± 585 large cytons and 1700 ± 564 ← intermediate cytons in the L5 segment of spinal cord. A reasonably close concordance was found between the average number of large cytons of spinal cord segments and the number of large-diameter myelinated fibers of ventral spinal roots (VSRs) (0.91, 0.94, and 0.98 for L3, L4 and L5 spinal cord segments and ventral spinal roots, respectively). For the ratio of the number of intermediate cytons to the number of intermediate axons the concordance was not as good (0.77, 0.85, and 1.14 for L3, L4 and L5 segments, respectively). Assuming that a cyton provides only one axon to VSR it is reasonable to infer from the studies that most large-diameter cytons are those of alpha motoneurons and that most of the intermediate-diameter cytons are those of gamma motor neurons. The greater number of axons than of cytons for the intermediate diameter group may be from a spurious inclusion of small-diameter axons (possibly pre-ganglionic autonomic fibers) with the intermediate-diameter group. On the average, the range of diameters of large-diameter cyton population in motoneuron columns was found to be 33 to 59 μm and for intermediate-diameter cytons was 24 to 33 μm. The total number of cytons per L3, L4 and L5 segments fell at a rate of ∞260, 175 and 200 per decade, respectively.

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