Axon diameter and myelin thickness—unusual relationships in dorsal root ganglia

Peter S. Spencer, Cedric S. Raine, Henryk WiśNiewski

Research output: Contribution to journalArticlepeer-review

54 Scopus citations

Abstract

Peripheral nerve fibers close to the sensory neurons of dorsal root ganglia displayed unusually thin myelin sheaths in relation to their axon diameter. Myelinated internodes along each fiber showed large differences in the numbers of myelin lamellae. These fibers are thought to represent spatial progression in degree of myelination as the axon egresses from the nonmyelinated glomerulus to the position of axonal bifurcation. This region is termed the initial complex of dorsal root ganglion cells. While the usual relationship between axon diameter and myelin sheath thickness is seen in the majority of dorsal root ganglion fibers, the fiber comprising each initial complex shows an atypical relationship in that the myelin sheath is unusually thin. Since the pattern of myelination in this small area is incongruous with previous reports attributing the control of myelin sheath thickness solely to axon diameter, the present findings indicate that other, unknown factors are operative in the control of myelination.

Original languageEnglish (US)
Pages (from-to)225-243
Number of pages19
JournalThe Anatomical Record
Volume176
Issue number2
DOIs
StatePublished - Jun 1973

ASJC Scopus subject areas

  • Anatomy
  • Agricultural and Biological Sciences (miscellaneous)

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