A touch receptor, occurring in the outer layer (epidermis) of hairless skin, that responds to sustained light pressure. Named after German anatomist Friedrich S. Merkel (1845–1919), these discs are found in large numbers in the fingertips, lips, and genitalia, where they are important in discriminating textures and shapes. Each consists of a sensory Merkel cell and associated sensory nerve ending, which conveys impulses to a sensory nerve.