Photopsin absorb light at different wavelengths as retinal-bound pigments. Humans have three different photoreceptor proteins ("photopsin" or "cone opsins") which are found in cone cells and which are responsible for colour vision: George Wald received the 1967 Nobel Prize in Physiology or Medicine for his experiments in the 1950s that showed the difference in absorbance by these photopsins (see image). Photopsin Photopsins (also known as Cone opsins) are the photoreceptor proteins found in the cone cells of the retina that are the basis of color vision. Iodopsin, the cone pigment system in chicken retina, is a close analog of the "visual
Retinal precursor cells retina is generated from the precursor cells within the inner layer of the optic cup, as opposed to the retinal pigment epithelium that originate from the outer layer of the optic cup. In general, the developing retina is organized so that the least-committed precursor cells are located in the periphery of the retina, while the committed cells are located in the center of the retina. The differentiation of retinal precursor cells into the mature cell types found in the retina is coordinated in time and space by factors within the cell as well as factors in the environment of the