Q.The outermost layer of mammalian skin (the epidermis) is composed of

Compound (stratified) epithelium consists of several layers of cells stacked one upon another, unlike the single layer of simple epithelium. New cells are produced continuously at the base of the stack and are pushed upward as they mature, flattening and eventually being shed or worn away at the free surface, so the tissue continuously renews itself from below even as its surface is abraded. The standard example is the epidermis of the skin, which is stratified squamous epithelium — flattened cells at the surface over several layers of less differentiated cells beneath. Because it is many cells thick, compound epithelium is specialised for protection against mechanical wear, abrasion, water loss and pathogen entry, a role that a single-layered simple epithelium could not withstand, though this thickness makes it less suited to rapid diffusion or absorption than simple epithelium is.