Photoreceptor cell cell depends upon only the number of photons absorbed. The different responses of the three types of cone cells are determined by the likelihoods that their respective photoreceptor proteins will absorb photons of different wavelengths. So, for example, an L cone cell contains a photoreceptor protein that more readily absorbs long wavelengths of light (i.e., more "red"). Light of a shorter wavelength can also produce the same response, but it must be much brighter to do so. The human retina contains about 120 million rod cells, and 6 million cone cells. The number and ratio of rods to cones varies
Retinal precursor cells Wnt11 is localized in the center of the developing retina and is suggested to play a role in precursor cell differentiation. This expression coincides with the fact that committed cells are located in the center of the developing retina while undifferentiated cells are concentrated in the periphery Fz5 expression is implicated in differentiation of retinal precursor cells to a neural fate. Retinal precursor cells Retinal precursor cells are biological cells that differentiate into the various cell types of the retina during development. In the vertebrate, these retinal cells differentiate into seven cell types, including retinal ganglion cells, amacrine cells, bipolar