Scanning Electron Micrograph (SEM) of the sole of the human foot, showing the parallel grooves and ridges of the epidermis: these ridges occur over underlying ridges in the dermis, and are comprised of flattened and partially overlapping squamous cells. The ridges of the foot ( as well as the fingerprints of the hand), appear in early embryonic development and are determined by hereditary factors. Here, the well-defined parallel ridges are seen (running left to right): the openings along the centre of the ridges are entrances to sweat gland ducts. Mag. X 56 (10x8).