Final answer:
The stratum lucidum is the specialized layer only found in the thick skin of the palms and soles, consisting of translucent dead keratinocytes, providing extra thickness and protection.
Step-by-step explanation:
The stratum lucidum is the layer that is only found on the palms of your hands and soles of your feet to provide an extra layer of thickness. The stratum lucidum is a smooth, seemingly translucent layer of the epidermis located just above the stratum granulosum and below the stratum corneum. This layer is characteristic of thick skin found in these areas of the body, as opposed to the thin skin that covers most of the other parts. The keratinocytes that compose the stratum lucidum are dead and flattened, densely packed with eleidin, a clear protein rich in lipids derived from keratohyalin, which gives these cells their transparent appearance and provides a barrier to water.
Contrary to what might be thought, the extra layer of epidermis found on the palms and soles (stratum lucidum) is not located on the very outer surface of the skin, that position is held by the stratum corneum.