title: Palisade endings in extraocular muscles of the monkey are immunoreactive for choline acetyltransferase and vesicular acetylcholine transporter.
abstract: OBJECTIVE
  To analyze palisade endings in extraocular muscles (EOMs) of a primate species and to examine our previous findings in cat that palisade endings are putative effector organs.
  
  
  METHODS
  Eleven monkeys (Macaca fascicularis) of both sexes, between 4 and 6 years of age were analyzed. Whole EOM myotendons were immunostained with four combinations of triple-fluorescent labeling and examined by confocal laser scanning microscopy. Labeling included antibodies against choline acetyltransferase (ChAT), vesicular acetylcholine transporter (VAChT), neurofilament, and synaptophysin. Muscle fibers were counterstained with phalloidin.
  
  
  RESULTS
  Palisade endings were observed in all monkey EOMs. Nerve fibers extended from the muscle into the tendon and looped back to divide into a terminal arborization (palisade ending) around a single muscle fiber tip. In approximately 30% of the cases, nerve fibers supplying palisade endings often established motor terminals outside the palisade complex. Nerve fibers forming palisade endings were ChAT-neurofilament positive. Axonal branches of palisade endings were ChAT-neurofilament positive as well. All palisade nerve terminals exhibited ChAT-synaptophysin immunoreactivity. Within the palisade complex, palisade nerve terminals exhibited VAChT immunoreactivity. All palisade nerve terminals were VAChT-synaptophysin immunoreactive.
  
  
  CONCLUSIONS
  The results confirm that in the monkey, palisade endings contain acetylcholine and are therefore most likely effector organs. Palisade endings are also present in human EOMs and because of their location at the myotendinous junction, these organs are of crucial interest for strabismus surgery.
authors.affiliation: Center of Anatomy and Cell Biology, Integrative Morphology Group, Medical University Vienna, Austria.
authors.forename: Kadriye Zeynep
authors.initials: KZ
authors.lastname: Konakci
authors.forename: Johannes
authors.initials: J
authors.lastname: Streicher
authors.forename: Wolfram
authors.initials: W
authors.lastname: Hoetzenecker
authors.forename: Ines
authors.initials: I
authors.lastname: Haberl
authors.forename: Michael Josef Franz
authors.initials: MJ
authors.lastname: Blumer
authors.forename: Grazyna
authors.initials: G
authors.lastname: Wieczorek
authors.forename: Josef Gottfried
authors.initials: JG
authors.lastname: Meingassner
authors.forename: Szabolcs Levente
authors.initials: SL
authors.lastname: Paal
authors.forename: Daniel
authors.initials: D
authors.lastname: Holzinger
authors.forename: Julius-Robert
authors.initials: JR
authors.lastname: Lukas
authors.forename: Roland
authors.initials: R
authors.lastname: Blumer
mesh_terms: D000818:Animals; D002795:Choline O-Acetyltransferase / Q000378:metabolism*; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D008252:Macaca fascicularis; D008297:Male; D018613:Microscopy, Confocal; D009046:Motor Neurons / Q000378:metabolism; D009411:Nerve Endings / Q000378:metabolism*; D009412:Nerve Fibers / Q000378:metabolism; D016900:Neurofilament Proteins / Q000378:metabolism; D009475:Neurons, Afferent / Q000378:metabolism*; D009801:Oculomotor Muscles / Q000294:innervation*; D016708:Synaptophysin / Q000378:metabolism; D050494:Vesicular Acetylcholine Transport Proteins / Q000378:metabolism*
chemical_list: D016900:Neurofilament Proteins; D016708:Synaptophysin; D050494:Vesicular Acetylcholine Transport Proteins; D002795:Choline O-Acetyltransferase