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Abstract #6670 Published in IGR 4-1
The retinal ganglion cell layer and visual acuity of the camel
Harman A; Dann J; Ahmat A; Macuda T; Johnston K; Timney BBehavior and Evolution 2001; 58: 15-27
The authors examined the retinal ganglion cell layer of the dromedary camel, Camelus dromedarius. They have estimated that there are eight million neurons in the ganglion cell layer of this large retina (mean area of 2,300 mm-2). However, approximately only one million are considered to be ganglion cells. The ganglion cells are arranged as two areas of high cell density, one in the temporal and one in the nasal retina. Densities of ganglion cells between these two high density regions is much lower, often less than 100 per mm-2. In between these two high density regions, on the nasal side of the optic nerve head, is a unique and dense vertical streak of mostly non-ganglion cells; the function of this specialization is unknown. On the basis of ganglion cell density, the authors estimate that the peak acuity in the dromedary camel is about 10 and 9.5 cycles per degree in the temporal and nasal high density regions, respectively, and falls to two to three cycles per degree in the central retina. Behavioral acuity was estimated for one bactrian camel and was found to be approximately 10 cyc deg-1. The camel has a retina with a mean thickness of 104 μm, less than the 143 μm thickness that was previously thought necessary for a retinal vasculature. Nevertheless, there is an extensive vitreal vasculature that does not appear to spare any retinal region.
Dr. A. Harman, Department of Psychology, University of Western Australia, Nedlands, WA 6907, Australia. Alison@psy.uwa.edu.au
Classification:
5 Experimental glaucoma; animal models
