Retina blood vessels and nerve cells. Confocal light micrograph of the retina, the lightsensitive membrane that lines the back of the eyeball. The tissue has been fluorescently stained. Ganglion cells (orange) receive visual information from photoreceptors beneath this surface, which is relayed to the brain by optic nerve fibres (red). Glial cells (green) offer structural support to the nerve cells. Blood vessels (blue) form branching networks across the retina to supply it with oxygen and nutrients. Magnification: 160x when printed 10 centimetres across.