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Fiber composition of the superior rectus extraocular muscle of the rhesus macaque

Fiber composition of the superior rectus extraocular muscle of the rhesus macaque The fiber composition of the superior rectus extraocular muscle of adult rhesus monkeys (Macaca mulatta) was examined in serial sections by light and electron microscopy as well as morphometry. Analyses allowed separation of singly versus multiply innervated fibers, and disclosed the morphology of these fibers and their topographical distribution within the muscle. Six morphologically distinct fiber types were found. The global layer of the muscle contains three singly innervated fibers (SIFs) and one multiply innervated fiber (MIF). The overlying orbital surface layer contains one SIF and one MIF, both showing morphological variation along their lenght. The MIFs of the orbital surface layer had not only multiple, relatively superficial endings along their length, but also endplatelike junctions in which the axonal terminals lie within synaptic clefts. These endplatelike junctions were confined to that region of the MIFs that had a morphology typical of “twitch” fibers; away from this region these MIFs had a morphology characteristic of “tonic” fibers. In contrast, the global MIFs showed constant morphology, and did not exhibit endplatelike endings. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Morphology Wiley

Fiber composition of the superior rectus extraocular muscle of the rhesus macaque

Journal of Morphology , Volume 174 (2) – Jan 1, 1982

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References (36)

Publisher
Wiley
Copyright
Copyright © 1982 Wiley Subscription Services
ISSN
0362-2525
eISSN
1097-4687
DOI
10.1002/jmor.1051740211
pmid
7175945
Publisher site
See Article on Publisher Site

Abstract

The fiber composition of the superior rectus extraocular muscle of adult rhesus monkeys (Macaca mulatta) was examined in serial sections by light and electron microscopy as well as morphometry. Analyses allowed separation of singly versus multiply innervated fibers, and disclosed the morphology of these fibers and their topographical distribution within the muscle. Six morphologically distinct fiber types were found. The global layer of the muscle contains three singly innervated fibers (SIFs) and one multiply innervated fiber (MIF). The overlying orbital surface layer contains one SIF and one MIF, both showing morphological variation along their lenght. The MIFs of the orbital surface layer had not only multiple, relatively superficial endings along their length, but also endplatelike junctions in which the axonal terminals lie within synaptic clefts. These endplatelike junctions were confined to that region of the MIFs that had a morphology typical of “twitch” fibers; away from this region these MIFs had a morphology characteristic of “tonic” fibers. In contrast, the global MIFs showed constant morphology, and did not exhibit endplatelike endings.

Journal

Journal of MorphologyWiley

Published: Jan 1, 1982

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