FIGURE 3.

Vertebrate retina structure and cellular composition. (A) Sagittal representation of the human eye. Light enters the eye through the lens and is projected onto the retina. (B) Stereotypical multilayered structure of the canonical vertebrate retina. Light transverses the entire retina until it reaches the photosensible PhRs at the distal ONL, in contact with RPE projections that are adjacent to the choroid plexus where choroidal vasculature supplies nutrients to the outer retina. In the OPL, PhR terminals contact projections from HC and BC, whose cell body reside in the INL. Projections from BC contact those from the GC and AC in the IPL. GC cell bodies reside in the GCL and their projections bundle in the NFL to create the optic nerve. MGCs span all of these layers and support the cells they contact. (C) Rod and cone PhRs cell structure. PhRs have an inner and outer segment. PhR OSs house membranous disks that house the photosensitive pigment responsible for light detection. The IS consists of the rest of the cell body and houses a mitochondrial cluster at the base of the OS. Abbreviations: AC, amacrine cell; BC, bipolar cell; GC, ganglion cell; HC, horizontal cell; INL, inner nuclear layer; IPL, inner plexiform layer; IS, inner segment; MGC, Müller glia cell; NFL, nerve fiber layer; ONL, outer nuclear layer; OPL, outer plexiform layer; OS, outer segment; PhR, photoreceptor; RPE, retinal pigment epithelium.