Biochemistry of the retina, illustration. The retina is the light-sensitive layer lining the rear of the interior of the eyeball. Light (yellow arrows) enters the eye from left. The retina's microscopic structure is shown here, with cells known as rods and cones. These include a bilayer membrane (upper right, expanded view at lower right) that contains the light-sensitive receptor protein rhodopsin (brown layer). The bilayer component of the membrane consists of chemicals called phospholipids (blue). Included here is the long-chain polyunsaturated fatty acid (LCP) component of the phospholipids. LCPs play a key role as a dietary source of chemicals for retinal development. For this artwork with labels, see image C046/1438.