title: Palisade Endings Are a Constant Feature in the Extraocular Muscles of Frontal-Eyed, But Not Lateral-Eyed, Animals.
abstract: OBJECTIVE
  To test whether palisade endings are a general feature of mammalian extraocular muscles (EOMs).
  
  
  METHODS
  Thirteen species, some frontal-eyed (human, monkey, cat, and ferret), and others lateral-eyed (pig, sheep, calf, horse, rabbit, rat, mouse, gerbil, and guinea pig) were analyzed. Palisade endings were labeled by using different combinations of immunofluorescence techniques. Three-dimensional reconstructions of immunolabeled palisade endings were done.
  
  
  RESULTS
  In all frontal-eyed species, palisade endings were a consistent feature in the rectus EOMs. Their total number was high and they exhibited an EOM-specific distribution. In particular, the number of palisade endings in the medial recti was significantly higher than in the other rectus muscles. In the lateral-eyed animals, palisade endings were infrequent and, when present, their total number was rather low. They were only found in ungulates (sheep, calf, pig, and horse) and in rabbit. In rodents (rat, guinea pig, mouse, and gerbil) palisade endings were found infrequently (e.g., rat) or were completely absent. Palisade endings in frontal-eyed species and in some lateral-eyed species (pig, sheep, calf, and horse) had a uniform morphology. They generally lacked α-bungarotoxin staining, with a few exceptions in primates. Palisade endings in other lateral-eyed species (rabbit and rat) exhibited a simplified morphology and bound α-bungarotoxin.
  
  
  CONCLUSIONS
  Palisade endings are not a universal feature of mammalian EOMs. So, if they are proprioceptors, not all species require them. Because in frontal-eyed species, the medial rectus muscle has the highest number of palisade endings, they likely play a special role in convergence.
authors.affiliation: Center of Anatomy and Cell Biology Integrative Morphology Group, MIC, Medical University Vienna, Vienna, Austria.
authors.forename: Roland
authors.initials: R
authors.lastname: Blumer
authors.affiliation: Center of Anatomy and Cell Biology Integrative Morphology Group, MIC, Medical University Vienna, Vienna, Austria.
authors.forename: Barbara
authors.initials: B
authors.lastname: Maurer-Gesek
authors.affiliation: CD-Laboratory for Extremity Reconstruction, Division of Plastic and Reconstructive Surgery, Medical University Vienna, Vienna, Austria.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Gesslbauer
authors.affiliation: Division of Clinical and Functional Anatomy, Department of Anatomy, Histology and Embryology, Innsbruck Medical University, Innsbruck, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Blumer
authors.affiliation: Division of Clinical and Functional Anatomy, Department of Anatomy, Histology and Embryology, Innsbruck Medical University, Innsbruck, Austria.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Pechriggl
authors.affiliation: Departamento de Fisiología, Facultad de Biología, Universidad de Sevilla, Sevilla, Spain.
authors.forename: María A
authors.initials: MA
authors.lastname: Davis-López de Carrizosa
authors.affiliation: Institute of Anatomy, Ludwig-Maximillian University, Munich, Germany.
authors.forename: Anja K
authors.initials: AK
authors.lastname: Horn
authors.affiliation: Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, Mississippi, United States.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: May
authors.affiliation: Center of Anatomy and Cell Biology Integrative Morphology Group, MIC, Medical University Vienna, Vienna, Austria 7Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria.
authors.forename: Johannes
authors.initials: J
authors.lastname: Streicher
authors.affiliation: Departamento de Fisiología, Facultad de Biología, Universidad de Sevilla, Sevilla, Spain.
authors.forename: Rosa R
authors.initials: RR
authors.lastname: de la Cruz
authors.affiliation: Departamento de Fisiología, Facultad de Biología, Universidad de Sevilla, Sevilla, Spain.
authors.forename: Ángel M
authors.initials: ÁM
authors.lastname: Pastor
mesh_terms: D000818:Animals; D002038:Bungarotoxins / Q000378:metabolism; D002415:Cats; D002417:Cattle; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D005289:Ferrets; D019084:Fluorescent Antibody Technique, Indirect; D007839:Functional Laterality / Q000502:physiology*; D005849:Gerbillinae; D006168:Guinea Pigs; D006736:Horses; D006801:Humans; D008251:Macaca; D051379:Mice; D018613:Microscopy, Confocal; D009046:Motor Neurons / Q000502:physiology*; D009411:Nerve Endings / Q000502:physiology*; D016900:Neurofilament Proteins / Q000378:metabolism; D009799:Ocular Physiological Phenomena; D009801:Oculomotor Muscles / Q000294:innervation*; D011434:Proprioception / Q000502:physiology; D011817:Rabbits; D051381:Rats; D011984:Sensory Receptor Cells / Q000378:metabolism*; D012756:Sheep; D013552:Swine
chemical_list: D002038:Bungarotoxins; D016900:Neurofilament Proteins; D002795:Choline O-Acetyltransferase
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