A novel nerve bundle containing thin muscle fibers in the posterior cricoarytenoid muscle of the marmoset
1 Departments of Integrated Basic Medical Research
2 Otolaryngology, Ehime University School of Medicine, Shizukawa, Toon, Ehime 791-0295, Japan
* To whom correspondence should be addressed. E-mail: desaki{at}m.ehime-u.ac.jp
We examined a novel nerve bundle in the posterior cricoarytenoid muscle of the marmoset. This intramuscular nerve bundle contained two thin muscle fibers about 10 µm in diameter, like intrafusal muscle fibers in the muscle spindle. These thin muscle fibers were individually surrounded by nerve bundles consisting of numerous nonmyelinated nerve fibers. Individual nerve axons contained clear synaptic vesicles and large granulated vesicles, being possibly cholinergic (parasympathetic) in nature. These nerve axons were often in contact with the muscle fiber with and without an interposing basal lamina. Two thin muscle fibers gradually terminated in the endoneural connective tissue around myelinated and nonmyelinated nerve fibers during their course. The innervation of thin muscle fibers in the novel nerve bundle is briefly discussed.
Keywords marmoset, myelinated and nonmyelinated nerve fibers, nerve bundle, posterior cricoarytenoid muscle, thin muscle fiber
Received 26 December 2006, accepted 8 February 2007