THE TOPOGRAPHY OF MAGNOCELLULAR PROJECTING GANGLION-CELLS (M-GANGLION CELLS) IN THE PRIMATE RETINA

The projection from the retina to the dorsal lateral geniculate nucleus in the primate arises from two morphologically distinct types of ganglion cells. The P-ganglion cells project to the parvocellular layers, the M-ganglion cells to the magnocellular layers. We have developed a neurofibrillar stain which stains the M-ganglion cell population with a high degree of selectivity allowing us to map their distribution across the retina. As with other ganglion cell types the M-ganglion cell density peaks close to the fovea and declines towards the periphery. At 1 mm from the fovea the proportion of M-ganglion cells ranges from 6 to 10% and then increases to about 8-10% over much of the retina except along the nasal horizontal meridian. Along the nasal horizontal meridian the percentage increases from 10% at 7 mm eccentricity to 20% or more at higher eccentricities. The increased percentage of M-ganglion cells in the nasal quadrant of the retina correlates with the relatively smaller dendritic trees of M-ganglion cells in this region.