Mcone

Mcone, commonly written as M-cone, refers to the medium-wavelength sensitive cone photoreceptor in the retina. Alongside S-cones (short-wavelength) and L-cones (long-wavelength), M-cones contribute to trichromatic color vision in humans and many other vertebrates. The M-cone photopigment is encoded by the M-opsin gene (OPN1MW) and has peak sensitivity near 530 nanometers.

Anatomically, M-cones are distributed throughout the retina with particular abundance in the macula and parafoveal regions, where color discrimination is most acute. In typical human retinas, L-cones and M-cones form the majority of the cone population, while S-cones are comparatively fewer. Signals from M-cones contribute to color and brightness processing through retinal color-opponent channels and onward to the visual cortex.

Genetics and variation: In humans, the M-opsin gene is located on the X chromosome in a cluster with the L-opsin gene. Variation and mispairing in this region can lead to red-green color vision deficiencies, most commonly deutan defects that reduce M-cone functionality or alter spectral sensitivity. Normal color vision relies on functional M-cones, though the exact spectral peak can vary among individuals and species.

In research and clinical context, M-cone function is assessed in color vision tests and retinal imaging studies. Understanding M-cones supports insights into color processing, visual development, and disorders affecting color perception.