Regenerating afferent fibers stimulate the recovery of Mauthner cell dendritic branching in the axolotl

L. A. Goodman, David Covell, P. G. Model

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

In the medulla of the axolotl (Ambystoma mexicanum), Mauthner cells (M-cells) occur as a pair of large identifiable neurons at the level of entry of the vestibular nerve (nVIII). Each receives synapses from the ipsilateral nVIII; the terminals can be identified as club endings and are restricted to a specific set of M-cell dendritic branches. We have examined these branches for morphologic changes following long-term deafferentation in the presence and absence of nerve regeneration. Deafferentation was brought about in a group of young larvae by unilaterally severing nVIII. The nerve was allowed to regenerate in half of the larvae. In those remaining, the nVIII ganglion was damaged to preclude or limit nerve regeneration. The contralateral side served as control. After 3 months survival, the larvae were killed and the medullae prepared for microscopy. To estimate the extent of nerve regeneration, axons in the experimental nVIII tract were counted and compared with the number in the control. The mean number of axons in the nVIII tract ipsilateral to intact ganglia indicated that 69% of the fibers had regenerated. In contrast, only 31% regenerated in larvae with damaged ganglia. Electron microscopic analysis of selected sections revealed that the mean number of nVIII terminals per section through M-cells ipsilateral to destroyed ganglia was significantly less than the mean number in analogous sections through either control cells or cells ipsilateral to intact ganglia. Control and experimental M-cells were reconstructed from serial sections. Deprived M-cells had significantly reduced dendritic branching patterns in the region that normally receives nVIII input. On the other hand, the extent of branching on cells receiving regenerated afferents from intact ganglia was like that of their contralateral controls. The distribution of dendritic branches on many reinnervated M-cells, however, was broader than that on control cells. Electron microscopic examination of the displaced dendritic branches (those extending into adjacent tracts) revealed that they received vestibular synapses. Thus, in some animals, regenerated vestibular fibers were not restricted to the nVIII tract. Deafferentation of the M-cell results in a reduction of dendritic branches in the region deprived of vestibular contacts. Restoration of the branches occurs only when nVIII terminals reestablish contact with the M-cell. These data indicate that regenerating afferents stimulate dendritic growth and that afferent innervation is essential in maintaining the dendritic branching pattern of target neurons.

Original languageEnglish (US)
Pages (from-to)3025-3034
Number of pages10
JournalJournal of Neuroscience
Volume8
Issue number8
StatePublished - 1988
Externally publishedYes

Fingerprint

Ambystoma mexicanum
Dendritic Cells
Ganglia
Nerve Regeneration
Larva
Synapses
Axons
Electrons
Vestibular Nerve
Neurons
Microscopy

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Regenerating afferent fibers stimulate the recovery of Mauthner cell dendritic branching in the axolotl. / Goodman, L. A.; Covell, David; Model, P. G.

In: Journal of Neuroscience, Vol. 8, No. 8, 1988, p. 3025-3034.

Research output: Contribution to journalArticle

Goodman, L. A. ; Covell, David ; Model, P. G. / Regenerating afferent fibers stimulate the recovery of Mauthner cell dendritic branching in the axolotl. In: Journal of Neuroscience. 1988 ; Vol. 8, No. 8. pp. 3025-3034.
@article{5d05ba9cfcb9499e9d5337ac15f41d47,
title = "Regenerating afferent fibers stimulate the recovery of Mauthner cell dendritic branching in the axolotl",
abstract = "In the medulla of the axolotl (Ambystoma mexicanum), Mauthner cells (M-cells) occur as a pair of large identifiable neurons at the level of entry of the vestibular nerve (nVIII). Each receives synapses from the ipsilateral nVIII; the terminals can be identified as club endings and are restricted to a specific set of M-cell dendritic branches. We have examined these branches for morphologic changes following long-term deafferentation in the presence and absence of nerve regeneration. Deafferentation was brought about in a group of young larvae by unilaterally severing nVIII. The nerve was allowed to regenerate in half of the larvae. In those remaining, the nVIII ganglion was damaged to preclude or limit nerve regeneration. The contralateral side served as control. After 3 months survival, the larvae were killed and the medullae prepared for microscopy. To estimate the extent of nerve regeneration, axons in the experimental nVIII tract were counted and compared with the number in the control. The mean number of axons in the nVIII tract ipsilateral to intact ganglia indicated that 69{\%} of the fibers had regenerated. In contrast, only 31{\%} regenerated in larvae with damaged ganglia. Electron microscopic analysis of selected sections revealed that the mean number of nVIII terminals per section through M-cells ipsilateral to destroyed ganglia was significantly less than the mean number in analogous sections through either control cells or cells ipsilateral to intact ganglia. Control and experimental M-cells were reconstructed from serial sections. Deprived M-cells had significantly reduced dendritic branching patterns in the region that normally receives nVIII input. On the other hand, the extent of branching on cells receiving regenerated afferents from intact ganglia was like that of their contralateral controls. The distribution of dendritic branches on many reinnervated M-cells, however, was broader than that on control cells. Electron microscopic examination of the displaced dendritic branches (those extending into adjacent tracts) revealed that they received vestibular synapses. Thus, in some animals, regenerated vestibular fibers were not restricted to the nVIII tract. Deafferentation of the M-cell results in a reduction of dendritic branches in the region deprived of vestibular contacts. Restoration of the branches occurs only when nVIII terminals reestablish contact with the M-cell. These data indicate that regenerating afferents stimulate dendritic growth and that afferent innervation is essential in maintaining the dendritic branching pattern of target neurons.",
author = "Goodman, {L. A.} and David Covell and Model, {P. G.}",
year = "1988",
language = "English (US)",
volume = "8",
pages = "3025--3034",
journal = "Journal of Neuroscience",
issn = "0270-6474",
publisher = "Society for Neuroscience",
number = "8",

}

TY - JOUR

T1 - Regenerating afferent fibers stimulate the recovery of Mauthner cell dendritic branching in the axolotl

AU - Goodman, L. A.

AU - Covell, David

AU - Model, P. G.

PY - 1988

Y1 - 1988

N2 - In the medulla of the axolotl (Ambystoma mexicanum), Mauthner cells (M-cells) occur as a pair of large identifiable neurons at the level of entry of the vestibular nerve (nVIII). Each receives synapses from the ipsilateral nVIII; the terminals can be identified as club endings and are restricted to a specific set of M-cell dendritic branches. We have examined these branches for morphologic changes following long-term deafferentation in the presence and absence of nerve regeneration. Deafferentation was brought about in a group of young larvae by unilaterally severing nVIII. The nerve was allowed to regenerate in half of the larvae. In those remaining, the nVIII ganglion was damaged to preclude or limit nerve regeneration. The contralateral side served as control. After 3 months survival, the larvae were killed and the medullae prepared for microscopy. To estimate the extent of nerve regeneration, axons in the experimental nVIII tract were counted and compared with the number in the control. The mean number of axons in the nVIII tract ipsilateral to intact ganglia indicated that 69% of the fibers had regenerated. In contrast, only 31% regenerated in larvae with damaged ganglia. Electron microscopic analysis of selected sections revealed that the mean number of nVIII terminals per section through M-cells ipsilateral to destroyed ganglia was significantly less than the mean number in analogous sections through either control cells or cells ipsilateral to intact ganglia. Control and experimental M-cells were reconstructed from serial sections. Deprived M-cells had significantly reduced dendritic branching patterns in the region that normally receives nVIII input. On the other hand, the extent of branching on cells receiving regenerated afferents from intact ganglia was like that of their contralateral controls. The distribution of dendritic branches on many reinnervated M-cells, however, was broader than that on control cells. Electron microscopic examination of the displaced dendritic branches (those extending into adjacent tracts) revealed that they received vestibular synapses. Thus, in some animals, regenerated vestibular fibers were not restricted to the nVIII tract. Deafferentation of the M-cell results in a reduction of dendritic branches in the region deprived of vestibular contacts. Restoration of the branches occurs only when nVIII terminals reestablish contact with the M-cell. These data indicate that regenerating afferents stimulate dendritic growth and that afferent innervation is essential in maintaining the dendritic branching pattern of target neurons.

AB - In the medulla of the axolotl (Ambystoma mexicanum), Mauthner cells (M-cells) occur as a pair of large identifiable neurons at the level of entry of the vestibular nerve (nVIII). Each receives synapses from the ipsilateral nVIII; the terminals can be identified as club endings and are restricted to a specific set of M-cell dendritic branches. We have examined these branches for morphologic changes following long-term deafferentation in the presence and absence of nerve regeneration. Deafferentation was brought about in a group of young larvae by unilaterally severing nVIII. The nerve was allowed to regenerate in half of the larvae. In those remaining, the nVIII ganglion was damaged to preclude or limit nerve regeneration. The contralateral side served as control. After 3 months survival, the larvae were killed and the medullae prepared for microscopy. To estimate the extent of nerve regeneration, axons in the experimental nVIII tract were counted and compared with the number in the control. The mean number of axons in the nVIII tract ipsilateral to intact ganglia indicated that 69% of the fibers had regenerated. In contrast, only 31% regenerated in larvae with damaged ganglia. Electron microscopic analysis of selected sections revealed that the mean number of nVIII terminals per section through M-cells ipsilateral to destroyed ganglia was significantly less than the mean number in analogous sections through either control cells or cells ipsilateral to intact ganglia. Control and experimental M-cells were reconstructed from serial sections. Deprived M-cells had significantly reduced dendritic branching patterns in the region that normally receives nVIII input. On the other hand, the extent of branching on cells receiving regenerated afferents from intact ganglia was like that of their contralateral controls. The distribution of dendritic branches on many reinnervated M-cells, however, was broader than that on control cells. Electron microscopic examination of the displaced dendritic branches (those extending into adjacent tracts) revealed that they received vestibular synapses. Thus, in some animals, regenerated vestibular fibers were not restricted to the nVIII tract. Deafferentation of the M-cell results in a reduction of dendritic branches in the region deprived of vestibular contacts. Restoration of the branches occurs only when nVIII terminals reestablish contact with the M-cell. These data indicate that regenerating afferents stimulate dendritic growth and that afferent innervation is essential in maintaining the dendritic branching pattern of target neurons.

UR - http://www.scopus.com/inward/record.url?scp=0023811028&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0023811028&partnerID=8YFLogxK

M3 - Article

C2 - 3411367

AN - SCOPUS:0023811028

VL - 8

SP - 3025

EP - 3034

JO - Journal of Neuroscience

JF - Journal of Neuroscience

SN - 0270-6474

IS - 8

ER -