Satb2 expressing retinal ganglion cells in three primate species: morphology and spatial distribution

Retinal ganglion cells (RGCs) are the output neurons of the retina, sending visual information to different targets in the brain. Each of these brain targets receive distinct features of the visual environment from specific types of RGCs which have unique morphological, molecular and functional profiles. The RGCs responsible for transmitting motion vision (parasol cells) and high acuity vision (midget cells) are well understood. However, at least 13 additional types of RGCs (named wide field ganglion cells) have been identified in primate retina but relatively little is known regarding their frequency, specific brain targets and molecular properties. Using immunohistochemistry and intracellular injections my research focuses on establishing potential reliable markers for specific wide-field ganglion cell types in human and non-human primate retinas. Intracellular injections using lipophilic dye ‘DiI’ after immunolabelling are used to reveal the morphology of ganglion cells. Double label immunohistochemistry is used to study the spatial distribution of identified ganglion cell types across the retina. This thesis demonstrates that the transcription factor Special AT-rich binding protein 2 (Satb2) is expressed by a subset of widefield ganglion cells in macaque, human and marmoset retinas, making up 3-4% of the ganglion cell population. In both macaque and human retina, Satb2 is expressed by large sparse cells but in macaque retina it is also expressed by narrow thorny cells. In marmoset retina, four types of widefield RGCs express Satb2 with the broad thorny cells making up the large majority. Molecular characterization and quantification of RGCs can further our understanding of how RGCs diversify to form types and their specific physiological roles in the visual pathway