C-Fiber Structure Varies with Location in Peripheral Nerve

Beth Brianna Murinson, John Wesley Griffin

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


Recent advances in regeneration and pain research have revealed gaps in the understanding of normal C-fiber anatomy. In the rat PNS, C-fiber axons assemble into Remak bundles, but beyond this, features of C-fiber organization are not defined. Systematic sampling and quantitation reveals that Remak bundles exiting from the L5 dorsal root ganglion (DRG) contain large numbers of axons, for example, 56% of unmyelinated axons were in bundles of >20 axons. This is different from distal nerve segments such as the hindpaw plantar nerve where the median number of axons per bundle is 3. The cross-sectional area of unmyelinated axons in dorsal root was homogeneous near the DRG but variability in axonal area increased near the spinal cord (p = 0.00001) and the mean axonal area was unchanged. Unmyelinated axons in peripheral nerve were almost always isolated from one another by Schwann cell processes; however, in dorsal root 7% to 9% of unmyelinated axons were immediately adjacent within pockets containing 2 or more axons. Remak bundles in the distal peripheral nerve clustered with other Remak bundles. We observe that multiple unmyelinated axons are juxtaposed within the C-fiber/Remak bundle and that the close association of afferent axons may have important functional implications.

Original languageEnglish (US)
Pages (from-to)246-254
Number of pages9
JournalJournal of neuropathology and experimental neurology
Issue number3
StatePublished - Mar 2004


  • Dorsal root
  • Peripheral nerve
  • Primary afferent neuron
  • Remak bundle
  • Sensory function
  • Sympathetic
  • Unmyelinated axon

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Neurology
  • Clinical Neurology
  • Cellular and Molecular Neuroscience


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