Topography of long- and middle-wavelength sensitive cone opsin gene expression in human and Old World monkey retina

The topographical distributions of the relative ratio of long- ~L! and middle- ~M! wavelength sensitive cone opsin messenger RNA ~mRNA! in human and baboon retinas were mapped using real-time polymerase chain reaction. The L:M mRNA ratio increased in a central-to-peripheral gradient in both species, being quite pronounced for humans.