Regional specialization of the ganglion cell density in the retina of the ostrich (Struthio camelus).

In this study, retinal whole-mount specimens were prepared and stained with 0.1% cresyl violet for the ganglion cell study in the ostrich (Struthio camelus). The total number, distribution, and size of these cells were determined in different retinal regions. The mean total number of ganglion cells (three retinas) was 1,435,052 with an average density of 652 cells/mm(2). The temporo-nasal area of the retina with high cell density were identified with the peak of 7525 cells/mm(2) in the central area. The size of most ganglion cells ranged from 113-403 microm(2), with smaller cells predominating along the temporo-nasal streak above the optic disc and larger cells comprising more of the peripheral regions. The average thickness of the retina was 196 microm. The central area was the thickest area (268.6 microm), whereas the peripheral area was the thinnest area. Thus, the specialization of ganglion cell densities, their sizes and the thickness of the retina support the notion that the conduction of visual information towards the brain from all regions of the retina is not uniform, and suggests that the temporo-nasal streak is the fine quality area for vision in ostriches.