Palisade endings are present in canine extraocular muscles and have a cholinergic phenotype

Stefanie Rungaldier, Christine Pomikal, Johannes Streicher, Roland Blumer*

*Corresponding author for this work

Research output: Journal article (peer-reviewed)Journal article

12 Citations (Scopus)

Abstract

Classical proprioceptors, like Golgi tendon organs and muscle spindles are absent in the extraocular muscles (EOMs) of most mammals. Instead, a nerve end organ was detected in the EOMs of each species including sheep, cat, rabbit, rat, monkey, and human examined so far: the palisade ending. Until now no clear evidence appeared that palisade endings are also present in canine EOMs. Here, we analyzed dog EOMs by confocal laser scanning microscopy, 3D reconstruction, and transmission electron microscopy. In EOM wholemount preparations stained with antibodies against neurofilament and synaptophysin we could demonstrate typical palisade endings. Nerve fibers coming from the muscle extend into the tendon. There, the nerve fibers turn 180° and return to branch into preterminal axons which establish nerve terminals around a single muscle fiber tip. Fine structural analysis revealed that each palisade ending in dog EOMs establish nerve terminals on the tendon. In some palisade endings we found nerve terminals contacting the muscle fiber as well. Such neuromuscular contacts have a basal lamina in the synaptic cleft. By using an antibody against choline acetyltransferase (ChAT) we proved that canine palisade endings are ChAT-immunoreactive. This study shows that palisade endings are present in canine EOMs. In line with prior findings in cat and monkey, palisade endings in dog have a cholinergic phenotype.

Original languageEnglish
Pages (from-to)199-203
Number of pages5
JournalNeuroscience Letters
Volume465
Issue number3
DOIs
Publication statusPublished - 20 Nov 2009
Externally publishedYes

Keywords

  • Choline acetyltransferase
  • Dog
  • Extraocular muscle
  • Palisade endings
  • Proprioception

ASJC Scopus subject areas

  • Neuroscience (all)

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