Skip to main content
Springer Nature Link
Log in

Ultrastructural studies of normal and degenerating mouse neuromuscular junctions

  • Published:
Journal of Neurocytology

Summary

A quantitative study of the ultrastructural changes occurring at degenerating motor axon terminals of the mouse hemidiaphragm in the first 26 h following unilateral phrenicotomy has been made. Several ultrastructural characteristics of axon terminals from normal diaphragms and phrenicotomized and control hemidiaphragms of phrenicotomized preparations were analyzed. Considerable swelling and disruption of mitochondria occurred in terminals of control hemidiaphragms at 3, 6 and 9 h post-phrenicotomy after which no more damage than that seen in normal terminals after fixation for electron microscopy was observed. At terminals of the phrenicotomized hemidiaphragm, much mitochondrial damage was observed from 3 h post-phrenicotomy onwards. In phrenicotomized hemidiaphragms all terminals had completely degenerated by 26 h post-phrenicotomy. Reduced synaptic vesicle population densities occurred during degeneration. At many axon terminals on phrenicotomized hemidiaphragms the population densities of synaptic vesicles were reduced compared with controls and vesicle aggregates were noted in many engulfed or partially engulfed nerve terminals.

These results are discussed with respect to the vesicle hypothesis for nerve-muscle transmission. The mechanisms underlying Schwann cell hyperactivity are also considered.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Subscribe and save

Springer+ Basic
$34.99 /Month
  • Get 10 units per month
  • Download Article/Chapter or eBook
  • 1 Unit = 1 Article or 1 Chapter
  • Cancel anytime
Subscribe now

Buy Now

Price includes VAT (Canada)

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  • Birks, R., Katz, B. andMiledi, R. (1960) Physiological and structural changes at the amphibian myoneural junction, in the course of nerve degeneration.Journal of Physiology (London) 150, 145–68.

    Google Scholar 

  • Bittner, G. D. andKennedy, D. (1970) Quantitative aspects of transmitter release.Journal of Cell Biology 47, 585–92.

    Google Scholar 

  • Ceccarelli, B., Hurlburt, W. P. andMauro, A. (1972) Depletion of vesicles from frog neuromuscular junctions by prolonged tetanic stimulation.Journal of Cell Biology 54, 30–8.

    Google Scholar 

  • Clark, P. J. andEvans, F. C. (1954) Distance to nearest neighbour as a measure of spatial relationships in populations.Ecology 35, 445–53.

    Google Scholar 

  • Couteaux, R. andPécot-Dechavassine, M. (1973) Données ultrastructurales et cytochimiques sur la mécanisme de libération de l'acetylcholine dans la transmission synaptique.Archives Italiennes de Biologie 111, 231–62.

    Google Scholar 

  • Fatt, P. andKatz, B. (1952) Spontaneous subthreshold activity at motor nerve endings.Journal of Physiology (London) 117, 109–28.

    Google Scholar 

  • Gage, P. W. andHubbard, J. I. (1965) Evidence for a Poisson distribution of miniature end-plate potentials and some implications.Nature (London) 208, 395–6.

    Google Scholar 

  • Heuser, J., Katz, B. andMiledi, R. (1971) Structural and functional changes of frog neuromuscular junctions in high calcium solutions.Proceedings of the Royal Society of London, Series B,178, 407–15.

    Google Scholar 

  • Heuser, J. andReese, T. S. (1973) Evidence for recycling of synaptic vesicle membrane during transmitter release at the frog neuromuscular junction.Journal of Cell Biology 57, 315–44.

    Google Scholar 

  • Hubbard, J. I. andKwanbunbumpen, S. (1968) Evidence for the vesicle hypothesis.Journal of Physiology (London) 194, 407–20.

    Google Scholar 

  • Hunt, C. C. andNelson, P. G. (1965) Structural and functional changes in the frog sympathetic ganglion following cutting of the presynaptic nerve fibres.Journal of Physiology (London) 177, 1–20.

    Google Scholar 

  • Katz, B. (1969)The release of neural transmitter substances. Liverpool: Liverpool University Press.

    Google Scholar 

  • Liley, A. W. (1957) Spontaneous release of transmitter substance in multi-quantal units.Journal of Physiology (London) 136, 595–605.

    Google Scholar 

  • Manolov, S. (1974) Initial changes in the neuromuscular synapses of denervated rat diaphragm.Brain Research 65, 303–16.

    Google Scholar 

  • Miledi, R. andSlater, C. R. (1968) Electrophysiology and electron-microscopy of rat neuromuscular junctions after nerve degeneration.Proceedings of the Royal Society of London, Series B 169, 280–306.

    Google Scholar 

  • Miledi, R. andSlater, C. R. (1970) On the degeneration of rat neuro-muscular junctions after nerve section.Journal of Physiology (London) 207, 507–28.

    Google Scholar 

  • Millonig, G. (1961) Advantages of a phosphate buffer for OsO4 solutions in fixation.Journal of Applied Physics 32, 1637.

    Google Scholar 

  • Nickel, E. andWaser, P. G. (1968) Elektronenmikroskopische Untersuchungen am Diaphragma der Maus nach einseitiger Phrenikotomi. I. Die degenerierende motorische Endplatte.Zeitschrift für Zellforschung und mikroskopische Anatomie 88, 278–96.

    Google Scholar 

  • Pysh, J. J. andWiley, R. G. (1974) Synaptic vesicle depletion and recovery in cat sympathetic ganglia electrically stimulatedin vivo.Journal of Cell Biology 60, 365–74.

    Google Scholar 

  • Rees, D. andUsherwood, P. N. R. (1972) Fine structure of normal and degenerating motor axons and nerve-muscle synapses in the locust,Schistocerca gregaria.Comparative Biochemistry and Physiology 43A, 83–101.

    Google Scholar 

  • Turner, P. T. andHarris, A. B. (1973) Ultrastructure of synaptic vesicle formation in cerebral cortex.Nature (London) 242, 57–8.

    Google Scholar 

  • Usherwood, P. N. R. (1963) Response of insect muscle to denervation. 2. Changes in neuromuscular transmission.Journal of Insect Physiology 9, 811–25.

    Google Scholar 

  • Usherwood, P. N. R. (1973) Release of transmitter from degenerating locust motorneurones.Journal of Experimental Biology 59, 1–16.

    Google Scholar 

  • Usherwood, P. N. R. andRees, D. (1972) Quantitative studies of the spatial distribution of synaptic vesicles within normal and degenerating motor axons of the locust,Schistocerca gregaria.Comparative Biochemistry and Physiology 43A, 103–18.

    Google Scholar 

  • Villegas, J. (1972) Axon-Schwann cell interaction in the squid nerve fibre.Journal of Physiology (London) 225, 275–96.

    Google Scholar 

  • Whittaker, V. P. (1971) Origin and function of synaptic vesicles.Annals of the NewYork Academy of Science,183, 21–32.

    Google Scholar 

  • Whittaker, V. P., Michaelson, I. A. andKirkland, R. J. A. (1964) The separation of synaptic vesicles from nerve ending particles (synaptosomes).Biochemical Journal 90, 293–305.

    Google Scholar 

  • Winlow, W. andUsherwood, P. N. R. (1975) Electrophysiological studies of normal and degenerating mouse neuromuscular junctions, (in preparation).

Download references

Author information

Author notes

  1. W. Winlow

    Present address: School of Biological Sciences, University of Sussex, BNI 9QG, Falmer, Brighton, Sussex

  2. P. N. R. Usherwood

    Present address: Department of Zoology, University of Nottingham, NG7 2RD, Nottingham

Authors and Affiliations

  1. Department of Zoology, University of Glasgow, G12 8QQ, Glasgow, Scotland

    W. Winlow & P. N. R. Usherwood

Authors
  1. W. Winlow
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. P. N. R. Usherwood
    View author publications

    You can also search for this author in PubMed Google Scholar

Rights and permissions

Reprints and permissions

About this article

Cite this article

Winlow, W., Usherwood, P.N.R. Ultrastructural studies of normal and degenerating mouse neuromuscular junctions. J Neurocytol 4, 377–394 (1975). https://doi.org/10.1007/BF01261371

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1007/BF01261371

Keywords

Search

Navigation