Survey of retinal ganglion cell morphology in marmoset

Abstract

In primate retina, the midget, parasol, and small bistratified cell populations form the large majority of ganglion cells. In addition, there is a variety of low-density wide-field ganglion cell types that are less well characterized. Here we studied retinal ganglion cells in the common marmoset, Callithrix jacchus, using particle-mediated gene transfer. Ganglion cells were transfected with an expression plasmid for the postsynaptic density 95-green fluorescent protein. The retinas were processed with established immunohistochemical markers for bipolar and/or amacrine cells to determine ganglion cell dendritic stratification. In total over 500 ganglion cells were classified based on their dendritic field size, morphology, and stratification in the inner plexiform layer. Over 17 types were distinguished, including midget, parasol, broad thorny, small bistratified, large bistratified, recursive bistratified, recursive monostratified, narrow thorny, smooth monostratified, large sparse, giant sparse (melanopsin) ganglion cells, and a group that may contain several as yet uncharacterized types. Assuming each characterized type forms a hexagonal mosaic, the midget and parasol cells account for over 80% of all ganglion cells in the central retina but only ∼50% of cells in the peripheral (>2 mm) retina. We conclude that the fovea is dominated by midget and parasol cells, but outside the fovea the ganglion cell diversity in marmoset is likely as great as that reported for nonprimate retinas. Taken together, the ganglion cell types in marmoset retina resemble those described previously in macaque retina with respect to morphology, stratification, and change in proportion across the retina.

Continuity between koniocellular layers of dorsal lateral geniculate and inferior pulvinar nuclei in common marmosets

“…Separate studies on K cells and IPul revealed similar inputs from retinal ganglion cells: Kwan et al (2018) demonstrated that retinal ganglion cells projecting to a sub-division of IPul in the marmoset had widefield morphologies including broad thorny, recursive bistratified, narrow thorny and large bistratified cells. Similar morphologies of retinal ganglion cells have been observed to project exclusively to the K layers of marmoset LGN (Szmajda et al, 2008;Percival et al, 2014;Masri et al, 2017). Two visual pathways from retina to MT via K cells or IPul are alternatives from retino-geniculate-cortical pathway.…”

Unravelling the subcortical and retinal circuitry of the primate inferior pulvinar

“…At least 20 types of RGCs have been classified in marmoset retina (Masri, Percival, Koizumi, Martin, & Grünert, ). As discussed in that study, the different types can be distinguished based on their dendritic field size, morphology, and stratification in the inner plexiform layer.…”

Visual properties of human retinal ganglion cells

“…So far, no physiological recordings of direction-selective cells have been published (but see [50]) and we could not detect such direction-selective behavior in our data set either (data not shown). Morphological studies identified potential candidates for primate direction-selective neurons [23,51,52]. These cells have a large dendritic field and hence they are much fewer in number than the smaller midget or parasol cells.…”