Cholinergic innervation of the chick basilar papilla
Article first published online: 25 FEB 2002
Copyright © 2002 Wiley-Liss, Inc.
Journal of Comparative Neurology
Volume 445, Issue 2, pages 159–175, 1 April 2002
How to Cite
Zidanic, M. (2002), Cholinergic innervation of the chick basilar papilla. J. Comp. Neurol., 445: 159–175. doi: 10.1002/cne.10160
- Issue published online: 25 FEB 2002
- Article first published online: 25 FEB 2002
- Manuscript Accepted: 11 DEC 2001
- Manuscript Revised: 11 MAY 2001
- Manuscript Received: 15 JUL 1998
- National Institute of Deafness and Communication Disorders. Grant Number: DC01508
- olivocochlear fibers;
- efferent inhibition;
Antibodies directed against choline acetyltransferase (ChAT), the synthesizing enzyme for acetylcholine (ACh) and a specific marker of cholinergic neurons, were used to label axons and nerve terminals of efferent fibers that innervate the chick basilar papilla (BP). Two morphologically distinct populations of cholinergic fibers were labeled and classified according to the region of the BP they innervated. The inferior efferent system was composed of thick fibers that coursed radially across the basilar membrane in small fascicles, gave off small branches that innervated short hair cells with large cup-like endings, and continued past the inferior edge of the BP to ramify extensively in the hyaline cell area. The superior efferent system was made up of a group of thin fibers that remained in the superior half of the epithelium and innervated tall hair cells with bouton endings. Both inferior and superior efferent fibers richly innervated the basal two thirds of the BP. However, the apical quarter of the chick BP was virtually devoid of efferent innervation except for a few fibers that gave off bouton endings around the peripheral edges. The distribution of ChAT-positive efferent endings appeared very similar to the population of efferent endings that labeled with synapsin antisera. Double labeling with ChAT and synapsin antibodies showed that the two markers colocalized in all nerve terminals that were identified in BP whole-mounts and frozen sections. These results strongly suggest that all of the efferent fibers that innervate the chick BP are cholinergic. J. Comp. Neurol. 445:159–175, 2002. © 2002 Wiley-Liss, Inc.