Unmyelinated axons of the auditory nerve in cats

David Kay Ryugo, L. W. Dodds, T. E. Benson, N. Y S Kiang

Research output: Contribution to journalArticle

Abstract

This paper describes some central terminations of type II spiral ganglion neurons as labeled by extracellular injections of horseradish peroxidase (HRP) into the auditory nerve of cats. After histological processing with diaminobenzidine, both thick (2-4 μm) and thin (0.5 μm) fibers of the auditory nerve were stained. Whenever traced, thick fibers always originated from type I spiral ganglion neurons and thin fibers always from type II ganglion neurons. Because the labeling of type II axons faded as fibers projected into the cochlear nucleus, this report is limited to regions of the ventral cochlear nucleus near the auditory nerve root. The central axons of type II neurons are unmyelinated, have simple yet variable branching patterns in the cochlear nucleus, and form both en passant and terminal swellings. Under the light microscope, most swellings are located in the neuropil but they are also found in the vicinity of cell bodies, nodes of Ranvier of type I axons, and blood vessels. Eighteen en passant swellings in the neuropil were located by light microscopy and resectioned for electron microscopy; two of these swellings exhibited ultrastructural features characteristic of chemical synapses. The data indicate that inputs from outer hair cells might be able to influence auditory processing in the cochlear nucleus through type II primary neurons.

Original languageEnglish (US)
Pages (from-to)209-223
Number of pages15
JournalJournal of Comparative Neurology
Volume308
Issue number2
StatePublished - 1991

Fingerprint

Cochlear Nerve
Cochlear Nucleus
Axons
Cats
Neurons
Spiral Ganglion
Neuropil
Outer Auditory Hair Cells
Ranvier's Nodes
Light
Horseradish Peroxidase
Ganglia
Synapses
Blood Vessels
Microscopy
Electron Microscopy
Injections

Keywords

  • cochlea
  • cochlear nucleus
  • hearing
  • horseradish peroxidase
  • primary afferents
  • spiral ganglion
  • synapse
  • type II neurons

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Ryugo, D. K., Dodds, L. W., Benson, T. E., & Kiang, N. Y. S. (1991). Unmyelinated axons of the auditory nerve in cats. Journal of Comparative Neurology, 308(2), 209-223.

Unmyelinated axons of the auditory nerve in cats. / Ryugo, David Kay; Dodds, L. W.; Benson, T. E.; Kiang, N. Y S.

In: Journal of Comparative Neurology, Vol. 308, No. 2, 1991, p. 209-223.

Research output: Contribution to journalArticle

Ryugo, DK, Dodds, LW, Benson, TE & Kiang, NYS 1991, 'Unmyelinated axons of the auditory nerve in cats', Journal of Comparative Neurology, vol. 308, no. 2, pp. 209-223.
Ryugo, David Kay ; Dodds, L. W. ; Benson, T. E. ; Kiang, N. Y S. / Unmyelinated axons of the auditory nerve in cats. In: Journal of Comparative Neurology. 1991 ; Vol. 308, No. 2. pp. 209-223.
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