The stratum lucidum reduces friction and shear forces between the surrounding layers of the epidermis. About.com explains that the stratum lucidum layer is only present in a few areas of the body that have very thick skin.
According to Wikipedia, the stratum lucidum only exists in the palms of the hands and the soles of the feet of humans. Its name comes from the Latin phrase for “clear layer,” which is a reference to the skin’s transparent appearance when viewed microscopically. The stratum lucidum is composed of up to five layers of dead cells, called keratinocytes. The boundaries of these keratinocytes are indistinct and the cells are filled with an intermediate form of keratin. The National Center for Biotechnology Information states that the layer contains enzymes and other chemicals that are secreted by granular cells.
According to the University of Texas Medical Branch, the stratum lucidum is only one of the five layers of the epidermis. The other four layers include the stratum basale, which produces the stem cells for the epidermis, the stratum spinosum and the stratum granulosum, which are all underneath the stratum lucidum. Immediately above the stratum lucidum is the outermost layer of the epidermis, the stratum corneum.