[Asymmetry in the structure of average and large neurons of the ganglion layer of the frog retina].

Morphometric analysis of the symmetry of middle and large ganglionic cells was performed on silver-impregnated retinal wholemounts of the frog. The nucleolus and the axis passing through the nucleolus in direction to optic disk were chosen as elements of symmetry characterizing the radial symmetry and bilateral one, respectively. It is demonstrated that the dendritic ramification angles of all cell types are smaller than 360 degrees and the angles of middle-type-GC are smaller than 180 degrees. In addition, their somata do not lie in the centre of the dendritic field, thus ganglionic cells have no radial symmetry. Directions of the axon and dendrites are opposite each other in the most of ganglionic cells, the terminals of dendrites being oriented from retinal centre to periphery in all quadrants of the retinal map. For estimation of bilateral symmetry the distance from the greatest remoted dendritic terminals to cell axis on the left and on the right from it was measured. Besides, the numbers of ramification knots and basal dendrites were counted. Most of ganglionic cells are asymmetrical in 2-3 mentioned structural parameters. Thus, the asymmetry in the structure of frog retinal neurons is rather norm than exception. Correlation between the asymmetry in ganglionic cell structure and functional asymmetry of their receptive fields is discussed.