title: Melanopsin-expressing ganglion cells in human retina: Morphology, distribution, and synaptic connections.
abstract: Melanopsin-expressing retinal ganglion cells are intrinsically photosensitive cells that are involved in non-image forming visual processes such as the pupillary light reflex and circadian entrainment but also contribute to visual perception. Here we used immunohistochemistry to study the morphology, density, distribution, and synaptic connectivity of melanopsin-expressing ganglion cells in four post mortem human donor retinas. Two types of melanopsin-expressing ganglion cells were distinguished based on their dendritic stratification near either the outer or the inner border of the inner plexiform layer. Outer stratifying cells make up on average 60% of the melanopsin-expressing cells. About half of the melanopsin-expressing cells (or 80% of the outer stratifying cells) have their soma displaced to the inner nuclear layer. Inner stratifying cells have their soma exclusively in the ganglion cell layer and include a small proportion of bistratified cells. The dendritic field diameter of melanopsin-expressing cells ranges from 250 (near the fovea) to 1,000 µm in peripheral retina. The dendritic trees of outer stratifying cells cover the retina independent of soma location. The dendritic fields of both outer and inner stratifying cells show a high degree of overlap with a coverage factor of approximately two. Melanopsin-expressing cells occur at an average peak density of between ∼20 and ∼40 cells/mm2at about 2 mm eccentricity, the density drops to below ∼10 cells/mm2at about 8 mm eccentricity. Both the outer and inner stratifying dendrites express postsynaptic density (PSD95) immunoreactive puncta suggesting that they receive synaptic input from bipolar cells.
authors.affiliation: Save Sight Institute and Department of Clinical Ophthalmology, The University of Sydney, Sydney, New South Wales, 2000, Australia.
authors.forename: Subha
authors.initials: S
authors.lastname: Nasir-Ahmad
authors.affiliation: Save Sight Institute and Department of Clinical Ophthalmology, The University of Sydney, Sydney, New South Wales, 2000, Australia.|Australian Research Council Centre of Excellence for Integrative Brain Function, The University of Sydney, Sydney, New South Wales, 2000, Australia.
authors.forename: Sammy C S
authors.identifier: 0000-0001-9220-6097
authors.initials: SCS
authors.lastname: Lee
authors.affiliation: Save Sight Institute and Department of Clinical Ophthalmology, The University of Sydney, Sydney, New South Wales, 2000, Australia.|Australian Research Council Centre of Excellence for Integrative Brain Function, The University of Sydney, Sydney, New South Wales, 2000, Australia.|School of Medical Sciences, The University of Sydney, Sydney, New South Wales, 2000, Australia.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Martin
authors.affiliation: Save Sight Institute and Department of Clinical Ophthalmology, The University of Sydney, Sydney, New South Wales, 2000, Australia.|Australian Research Council Centre of Excellence for Integrative Brain Function, The University of Sydney, Sydney, New South Wales, 2000, Australia.|School of Medical Sciences, The University of Sydney, Sydney, New South Wales, 2000, Australia.
authors.forename: Ulrike
authors.identifier: 0000-0002-9595-8152
authors.initials: U
authors.lastname: Grünert
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000166:cytology / Q000378:metabolism; D012165:Retinal Ganglion Cells / Q000166:cytology* / Q000378:metabolism*; D017299:Rod Opsins / Q000378:metabolism*; D000099210:Melanopsin
chemical_list: D017299:Rod Opsins; D000099210:Melanopsin
keywords: RRID: AB_10807979; RRID: AB_2079751; intrinsically photosensitive ganglion cells; primate retina; synaptic input