Figure 1. Cross s%ectional diagrams of the mammalian retina. All vertebrate retinas are composed of three layers of nerve cell bodies and two layers of synapses. The light transducers, photoreceptors (rods and cones), are positioned outermost in the retina, against the retinal pigment epithelium (rpe) and choroid (not shown). Light is transduced in the outer segments (OS) of rods and cones. The outer nuclear layer (ONL) contains cell bodies of the rods and cones; the inner nuclear layer (INL) contains cell bodies of the bipolar, horizontal and amacrine cells. The output neurons of the retina, ganglion cells, lie in the ganglion cell layer (GCL). Ganglion cell axons course through the nerve fiber layer (NFL) abutting the inner limiting membrane (ILM). In between these cell layers are two synaptic, or plexiform, layers. Synaptic connections between photoreceptors, and bipolar cells and horizontal cells are contained in the outer plexiform layer (OPL) while synapses among bipolar cells, amacrine cells and ganglion cells are found in the inner plexiform layer (IPL). The resident glial cell of the retina, the Müller cell spans nearly the entire thickness of the neural retina. Its end feet adhere to the ILM at the basal surface and it forms adherens junctions with photoreceptors at the apical surface, forming the outer limiting membrane (OLM). Modified with additions from original drawings of Schultze; Ramon y Cajal.