RELATIONSHIP BETWEEN NUMBERS OF RETINAL GANGLION-CELLS AND LATERAL GENICULATE NEURONS IN THE RHESUS-MONKEY

Studies of the numbers of retinal ganglion cells and lateral geniculat e nucleus (LGN) neurons in primates suggest that the numbers of both t ypes of neurons may vary over a two-fold range from one individual to another. This raises the question of whether the numbers of ganglion c ells and LGN neurons are related or vary independently from individual to individual. We used stereological procedures to obtain unbiased es timates of the numbers of both cell types in seven rhesus monkeys. We found no significant correlation (r(s) = -0.21) between the numbers of retinal and LGN cells in the same animals. In agreement with previous studies, the average ratio of the number of retinal ganglion cells th at project to the LGN and the number of LGN cells was approximately 1: 1. However, this ratio varied over a two-fold range, from 0.78:1 to 1. 64:1, in individual animals. These results have important implications for understanding the mechanisms of retino-geniculate development and for understanding the connectional wiring between the retina and LGN.