SIZE AND DISTRIBUTION OF RETINAL GANGLION-CELLS IN THE ST KITTS GREENMONKEY (CERCOPITHECUS-AETHIOPS SABEUS)

The topographical distribution of density and the soma size of retinal ganglion cells (RGCs) were studied in the St. Kitts green monkey (Cer copithecus aethiops sebeus). The total number of RGCs, estimated from light microscopic analysis of wholemounted and of transversely section ed retinae, ranged between 1,183,721 and 1,273,715 (mean 1,228,646). T hese estimates are comparable to the number of optic nerve fibres (1,2 20,000) estimated from semithin sections. The topographic distribution of RGCs shows a strong centroperipheral gradient. The soma size distr ibution of RGCs in Nissl-stained flatmounts falls within a range of be tween 5.7 mu m and 22.9 mu m and is comparable to other primate specie s. Somata of RGCs were found to be generally smaller within the fovea than in peripheral regions. Ganglion cells, as reported for other diur nal primates, are nonuniformly distributed with a slight nasotemporal elongation of isodensity contours, and they exhibit nasotemporal asymm etry in the frequency distribution of soma size. The topography of the RGC distribution of this semiarboreal, ground-dwelling monkey is simi lar to what has been found in other diurnal Old World species. (C) 199 7 Wiley-Liss, Inc.