A QUANTITATIVE STUDY OF GANGLION-CELLS IN THE GERMAN-SHEPHERD DOG RETINA

As in the number of mammals, the most prominent feature of the ganglio n-cell layer in the retina of the German shepherd dog is the sharp inc rease in the density of ganglion cells in the central area. There is a n area of maximum density and also a 'cat-like' visual streak, located dorsal to the optic disc. The isodensity lines of ganglion-cell distr ibution is roughly concentric. Their values vary from 530-13 000 cells /mm(2) in the central area, with the cells densely packed, to 1000 cel ls/mm(2) or less in the periphery, where the cells are sparsely distri buted. There were some individual differences amongst the animals stud ied, although all of them were pure-bred dogs. This suggests that the configuration of the retina in the canine species is not only dependen t on the breed itself but also on some other parameters such as phylog enetic heritage, environment, aptitude, lifestyle, or even training.