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
AII amacrine cells AII amacrine cells AII amacrine cells are a subtype of amacrine cells present in the retina of mammals. AII amacrine cell serve the critical role of transferring light signals from rod photoreceptors to the retinal ganglion cells (which contain the axons of the optic nerve) The Classical Rod Pathway described the role of AII amacrine cells in the mammalian retina. This can be summarised as follows: (Once activated, the AII amacrine cell then modulates the cone ON and OFF channels): The ON- and OFF- cone bipolar cells in turn contact the ON- and OFF-centre retinal ganglion cells, respectively. "Note: A