The distribution and size of ganglion cells in the retina of the pigmented rabbit: A quantitative analysis

The distribution and soma diameters of retinal ganglion cells have been examined in whole mounted retinae of pigmented rabbits. Maps of the distribution of ganglion cells confirmed several features of earlier descriptions, but generally showed lower density values and yielded lower total ganglion cell counts (250,000-270,000). The maximum ganglion cell density encountered in each retina and its retinal location both varied between rabbits. As previously reported, the dominant feature of the rabbit's retina is a strongly developed visual streak (Hughes, '71) but some evidence of an area centralis-like specialization was found. This appears not as the area of peak gangion cell density, but as a concentration of large (greater than or equal to 20 micron in diameter) ganglion cells at the temporal end of the visual streak, 2-3 mm from the temporal margin of the retina. In one rabbit in which the optic tract was sectioned five months previously, the density distribution of large retinal ganglion cells in the retinae has been mapped. These maps indicate that the nasotemporal division for large ganglion cells in the rabbit retina is approximately centered on the area of their maximum density. It has previously been reported that in the cat the area centralis is characterized by an aggregation of smaller diameter ganglion cells of a particular functional type (Stone, '65, '78). It is possible that areas of retinal which subserve area centralis-like functions are represented not simply by localized increases in ganglion cell density, but by changes in the relative proportions of ganglion cell types, which are reflected in the changing relative densities of ganglion cell soma diameter groups.