PHOTOPIGMENT

noun. a substance in a retinal rod or retinal cone which interacts with light to initiate a chemical cascade resulting in the conversion of light energy into an electrical signal. All rods contain the rhodopsin, while cones have one of three various photo pigments !!!!!!!!!!iodopsins!!!!!!!!!!, each with a various wavelength sensitivity !!!!!!!!!!see long-wavelength pigment- medium-wavelength pigment- short'-wavelength pigment!!!!!!!!!!. Photopigment is located in disks of membrane in the outer segment of a rod or cone. Commonly referred to as visual pigment,