List the five layers of the epidermis from most internal to most external and describe the function of each layer.

The most internal layer of the epidermis is the stratum basale which contains melanocytes. Melanocytes produce melanin to protect the DNA. The cells of the stratum basale are the only cells that are capable of cell division. The stratum basale is attached to the underlying dermis. The stratum spinosum is superficial to  the stratum basale.  Stratum granulosum is superficial to the struatum spinosum. The stratum granulosum is three to five layers thick and contains keratohyalin granules, which produce keratin, a water proof protein.Stratum lucidum is superficial to stratum granulosum, but only in thick skin, which is on the palms and soles. Stratum corneum is about 25 cells thick and is the most superficial layer. It is dead and the cells are completely filled with keratin, which is waterproof. The many layers of dead skin protect from abrasion and are the first line of defense against any foreign bacteria, debris or virus.