Study of Ganglion Cell Topography of the Retina in Buffaloes (Bos bubalis)

Abstract

The total number, distribution and size of retinal ganglion cells of buffalo (Bos bubalis) were described in four wholemounts of the retina stained by the Nissl method. The ganglion cells were observed in the area of visual streak, dorsotemporal, dorsonasal and ventral parts of the retina. Soma size was measured from samples taken from these different retinal regions. Ganglion cells were concentrated along the horizontal visual streak, which lies dorsal to the optic disc. The mean value of the total number of ganglion cells was 1, 527, 965. The peak ganglion cell density totaled 4, 617/mm2 at the temporal end of the streak. The distribution of ganglion cells varied in different parts of the retina where it was highest in the dorsotemporal part, average in the dorsonasal part and lowest in the ventral part. The sizes of ganglion cells varied between 10-26μm, The small cells were more in the visual streak than in the other areas while the large cells were more in the ventral part of the retina. The visual acuity was calculated from the density of ganglion cells. The visual acuity in the visual streak was 14.3 cycles/degree compared with 2.3 cycles/degree in the periphery. The retinal area of the buffalo's eye ranged from 2, 414 to 3, 060mm2 (mean: 2, 667mm2). The thickness of the retina ranged from 290μm close to the center to 140μm peripherally. Thus, theresults suggest that the visual streak area is the highest quality area of vision; followed by the dorsotemporal area while the ventral area is the lowest.