Healing skin ulcer. Coloured light micrograph of stratified squamous epithelial cells (purple, upper left), which are flat and scale-like in structure, growing over an ulcer (pink, right). At upper right is a scab (red), which forms the surface of the ulcer. The large red regions throughout the skin layer (at lower right for example) are dilated blood vessels. This ensures that inflammatory cells can easily reach the area to promote healing.