Ascending unmyelinated primary afferent fibers in the dorsal funiculus

J. T. Patterson, P. A. Head, D. L. McNeill, K. Chung, R. E. Coggeshall

Research output: Contribution to journalArticlepeer-review

55 Scopus citations


The primary purpose of the present study is to obtain evidence as to the destination of the recently discovered unmyelinated primary afferent fibers in the mammalian dorsal funiculus. To do this rat dorsal roots were transected unilaterally from segments T8 or T9 caudally, and the numbers of axons were determined in the C3 fasciculus gracilis in normal animals and from both sides of the rhizotomied animals. In addition, C3 fasciculus gracilis counts were done in animals that had complete T6 or T10 spinal transections. The data indicate that there is an 80% loss of unmyelinated axons ipsilaterally and a 60% loss contralaterally in the fasciculus gracilis of the rhizotomied animals. These findings are interpreted as indicating that a significant fraction of the unmyelinated fibers in the fasciculus gracilis ascend, presumably to the nucleus gracilis in the brain stem, and also that a significant number of these fibers branch. We also provide evidence for contralateral myelinated primary afferent fiber projection in the fasciculus gracilis and show that the myelinated primary afferent fibers seem to be a more diverse population than the unmyelinated primary afferent fibers in the C3 fasciculus gracilis.

Original languageEnglish (US)
Pages (from-to)384-390
Number of pages7
JournalJournal of Comparative Neurology
Issue number3
StatePublished - Dec 15 1989


  • dorsal rhizotomy
  • fasciculus gracilis
  • unmyelinated axons

ASJC Scopus subject areas

  • General Neuroscience


Dive into the research topics of 'Ascending unmyelinated primary afferent fibers in the dorsal funiculus'. Together they form a unique fingerprint.

Cite this