Afferent innervation of outer and inner hair cells is normal in neonatally de-efferented cats

M. Charles Liberman, Daniel F. O'Grady, Leslie W. Dodds, Joann McGee, Edward J. Walsh

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

It has been hypothesized that normal pruning of exuberant branching of afferent neurons in the developing cochlea is caused by the arrival of the olivocochlear efferent neurons and the resulting competion for synaptic sites on hair cells. This hypothesis was supported by a report that afferent innervation density on mature outer hair cells (OHCs) is elevated in animals de-efferented at birth, before the olivocochlear system reaches the outer hair cell area (Pujol and Carlier [1982] Dev. Brain Res. 3:151-154). In the current study, this claim was evaluated quantitatively at the electron microscopic level in four cats that were de-efferented at birth and allowed to survive for 6-11 months. A semiserial section analysis of 156 OHCs from de-efferented and normal ears showed that, although de-efferentation essentially was complete in all four cases, the number and distribution of afferent terminals on OHCs was indistinguishable from normal, and the morphology of afferent synapses was normal in both the inner hair cell area and the OHC area. Thus, the postnatal presence of an efferent system is not required for the normal development of cochlear afferent innervation, and the synaptic competition hypothesis is not supported. (C) 2000 Wiley-Liss, Inc.

Original languageEnglish (US)
Pages (from-to)132-139
Number of pages8
JournalJournal of Comparative Neurology
Volume423
Issue number1
DOIs
StatePublished - Jul 17 2000

Fingerprint

Outer Auditory Hair Cells
Inner Auditory Hair Cells
Cats
Cochlea
Efferent Neurons
Parturition
Afferent Neurons
Synapses
Ear
Electrons
Brain

Keywords

  • Cochlea
  • Development
  • Olivocochlear

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Afferent innervation of outer and inner hair cells is normal in neonatally de-efferented cats. / Liberman, M. Charles; O'Grady, Daniel F.; Dodds, Leslie W.; McGee, Joann; Walsh, Edward J.

In: Journal of Comparative Neurology, Vol. 423, No. 1, 17.07.2000, p. 132-139.

Research output: Contribution to journalArticle

Liberman, M. Charles ; O'Grady, Daniel F. ; Dodds, Leslie W. ; McGee, Joann ; Walsh, Edward J. / Afferent innervation of outer and inner hair cells is normal in neonatally de-efferented cats. In: Journal of Comparative Neurology. 2000 ; Vol. 423, No. 1. pp. 132-139.
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