Retina bipolar cell it, either through a metabotropic (ON) or ionotropic (OFF) receptor. However, the mechanism for producing the monochromatic surround of the same receptive field is under investigation. While it is known that an important cell in the process is the horizontal cell, the exact sequence of receptors and molecules is unknown. Retina bipolar cell As a part of the retina, bipolar cells exist between photoreceptors (rod cells and cone cells) and ganglion cells. They act, directly or indirectly, to transmit signals from the photoreceptors to the ganglion cells. Bipolar cells are so-named as they have a central body from which two
Evolution of the eye light would activate exactly the same patch of photo-sensitive cells regardless of its direction, the "cup" shape of the pit eyes allowed limited directional differentiation by changing which cells the lights would hit depending upon the light's angle. Pit eyes, which had arisen by the Cambrian period, were seen in ancient snails, and are found in some snails and other invertebrates living today, such as planaria. Planaria can slightly differentiate the direction and intensity of light because of their cup-shaped, heavily pigmented retina cells, which shield the light-sensitive cells from exposure in all directions except for the single opening for