Rod cells

Rod cells are one of the two types of cell found in the retina, the other being Cone cells, both of which are classified as photoreceptor cells. 

Rod cells are monochromatic, meaning that they are receptive to only one coulour and are used in Scotopic vision (under low light conditions), this is because the rod cells become bleached at high light intensities. The pigament within Rod Cells is called Rhodopsin and is made up of two components, a protein; Opsin and a Vitamin A derivative 11-Cis-Retinal. When under low light conditions these two compounds are bound as Rhodopsin allowing the Rods to function, when light intensity increases these become bleached and split, thus the Rods are unable to function.