Topography of cones and rods in the tree shrew retina.
The topographical distribution of cones and rods in the tree shrew retina was analysed quantitatively in whole-mounted retinae and horizontal semithin sections stained with cresyl violet or toluidine blue. The outer nuclear layer consists of a single layer of photoreceptor nuclei with the rod nuclei slightly displaced towards the outer plexiform layer. This facilitated quantification of the photoreceptor populations. The density of cones ranges from 12,000/mm2 in the peripheral retina to a maximum of 36,000/mm2 in the inferior retina. Unlike ganglion cell density, the density of cones does not peak in the temporal retina. Rod density, between 500/mm2 and 3,500/mm2, also peaks in the inferior retina, but not in the same region as cone density. Rods constitute from 1 to 14% of the photoreceptor population, depending on retinal location, and have a local minimum at the central area. Amongst the cones a regularly arrayed subpopulation of presumed blue-sensitive cones is distinguished by its special staining properties. These cones constitute between 4 and 10% of the cone population depending on retinal location. A second, irregularly spaced, subpopulation of possibly pathological cones is also described.
Müller
B
B
Max-Planck-Institut für Hirnforschung, Frankfurt/Main, Federal Republic of Germany.
Peichl
L
L
D000818:Animals; D001931:Brain Mapping; D005260:Female; D008297:Male; D009457:Neuroglia / Q000033:anatomy & histology; D010786:Photoreceptor Cells / Q000033:anatomy & histology*; D012160:Retina / Q000033:anatomy & histology* / Q000166:cytology; D014418:Tupaiidae / Q000033:anatomy & histology*