Köppl, Christine and Wegscheider, Andrea and Gleich, Otto and Manley, Geoffrey A. (2000) A quantitative study of cochlear afferent axons in birds. Hearing Research 139 (1-2), pp. 123-143.
Download (2MB) - Repository staff only
This paper is a comparative study of auditory-nerve morphology in birds. The chicken (Gallus gallus), the emu (Dromaius novaehollandiae) and the starling (Sturnus vulgaris) were chosen as unspecialised birds that have already been used in auditory research. The data are discussed in comparison to a similar earlier study on the barn owl, a bird with highly specialised hearing, in an attempt to separate general avian patterns from species specialisations. Average numbers of afferent fibres from 8775 (starling) to 12 406 (chicken) were counted, excluding fibres to the lagenar macula. The number of fibres representing different frequency ranges showed broad maxima in the chicken and emu, corresponding to hearing ranges of best sensitivity and/or particular behavioural relevance. Mean axon diameters were around 2 μm in the chicken and starling, and around 3 μm in the emu. Virtually all auditory afferents were myelinated. The mean thickness of the myelin sheaths was between 0.33 μm (starling) and 0.4 μm (emu). There was a consistent pattern in the diameters of axons deriving from different regions. Axons from very basal, i.e. highest-frequency, parts of the basilar papilla were always the smallest. In the emu and the chicken, axons from the middle papillar regions were, in addition, larger than axons innervating apical regions.
|Institutions:||Medicine > Lehrstuhl für Hals-Nasen-Ohren-Heilkunde|
|Keywords:||Auditory; Basilar papilla; Eighth nerve; Barn owl; Chicken; Myelination|
|Subjects:||500 Science > 590 Zoological sciences|
600 Technology > 610 Medical sciences Medicine
|Refereed:||Yes, this version has been refereed|
|Created at the University of Regensburg:||Partially|
|Deposited On:||11 Sep 2008 14:17|
|Last Modified:||20 Jul 2011 21:21|