Afferent Innervation Patterns of the Pigeon Horizontal Crista Ampullaris

• Published in: Journal of neurophysiology Vol. 96; no. 6; pp. 3293 - 3304
• Main Authors: Haque, Asim, Huss, David, Dickman, J. David
• Format: Journal Article
• Language: English
• Published: United States Am Phys Soc 01-12-2006
• Subjects: Animals; Axons - physiology; Biotin - analogs & derivatives; Columba livia; Columbidae - physiology; Dextrans; Fluorescent Dyes; Immunohistochemistry; Male; Microscopy, Electron, Scanning; Nerve Fibers - physiology; Neurons, Afferent - physiology; Presynaptic Terminals - physiology; Saccule and Utricle - innervation; Semicircular Canals - innervation; Semicircular Canals - physiology; Vestibule, Labyrinth - innervation; Vestibule, Labyrinth - physiology
• ISSN: 0022-3077; 1522-1598
• DOI: 10.1152/jn.00930.2005

1 Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri; and 2 School of Medicine, University of Mississippi Medical Center, Jackson, Mississippi
Submitted 2 September 2005;
accepted in final form 13 August 2006
The vestibular semicircular canals are responsible for detection of rotational head motion although the precise mechanisms underlying the transduction and encoding of movement information are still under study. In the present investigation, we utilized neural tracers and immunohistochemistry to quantitatively examine the topology and afferent innervation patterns of the horizontal semicircular canal crista (HCC) in pigeons ( Columba livia ). Two hundred and eighty-six afferents from five horizontal canal organs were identified of which 92 units were sufficiently labeled and isolated to perform anatomical reconstructions. In addition, a three-dimensional contour map of the crista was constructed. Bouton afferents were located only in the peripheral regions of the receptor epithelium. Bouton afferents had the most complex innervation patterns with significantly longer and more numerous branches as well as a higher branch order than any other fiber type. Bouton fibers also contained significantly more bouton terminals than did dimorph afferents. Calyx afferents were located only in the apex and central planar regions. Calyx fibers had the largest axonal diameters yet the smallest fiber lengths and innervation areas, the fewest number of branches, the lowest branch order, and the fewest total number of terminals of all fiber types. Dimorph afferents were located throughout the central crista with afferent terminations that were larger and more complex than calyx fibers but less so than bouton fibers. Overall, the pigeon HCC morphology and innervation shares many common features with those of other animal classes.
Address for reprint requests and other correspondence: Dr. J. David Dickman, Dept. of Anatomy and Neurobiology –Box 8108, Washington University School of Medicine, 660 S. Euclid, St. Louis, MO 63110 (E-mail: ddickman{at}wustl.edu )