Lumbar motoneurons of man: I) Number and diameter histogram of alpha and gamma axons of ventral root

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

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Abstract

The numbers of large and intermediate diameter myelinated fibers of 17 ventral lumbar (L3, L4 and L5) spinal roots (vsr) of man (ages 17-81 years) have been evaluated using the improved methods of histologic processing and morphometry now available, semi-automatic methods of measurement and programmed calculation and plotting. A population of small diameter myelinated fibers as found in thoracic (T11) vsr, which are presumed to be preganglionic sympathetic fibers, were essentially absent from L3, L4 and L5 roots. On the average, there were 5716 (70%) large diameter fibers and 2625 (30%) intermediate diameter fibers in the L3 ventral spinal root. Comparable figures for L4 vsr were 4900 (70%) and 2152 (30%) and for L5 vsr were 5043 (75%) and 1559 (25%). On the assumption that these lumbar roots contain few if any small diameter myelinated pre-gangionic sympathetic adons, the large diameters fibers correspond to alpha motoneuron axons and the small diameter fibers to gamma motoneuron axons. With age, a decrease in the number of myelinated fibers was estimated to be 350 fibers per decade (∞5% per decade).

Original languageEnglish (US)
Pages (from-to)853-860
Number of pages8
JournalJournal of Neuropathology and Experimental Neurology
Volume36
Issue number5
StatePublished - 1977

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Spinal Nerve Roots
Motor Neurons
Axons
Adrenergic Fibers
Thorax
Population

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Neuroscience(all)

Cite this

Lumbar motoneurons of man : I) Number and diameter histogram of alpha and gamma axons of ventral root. / Kawamura, Y.; Okazaki, H.; O'Brien, P. C.; Dyck, Peter J.

In: Journal of Neuropathology and Experimental Neurology, Vol. 36, No. 5, 1977, p. 853-860.

Research output: Contribution to journalArticle

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