The stratum lucidum is a layer found only in the thick skin of the palms and soles of the feet. It's a clear, translucent layer located above the stratum granulosum and below the stratum corneum in the epidermis.
Understanding Skin Layers
The skin has several layers:
- Epidermis: The outermost layer, providing protection. The epidermis itself contains multiple sub-layers, including the stratum corneum (the most superficial layer exposed to the environment), and the stratum lucidum (only present in thick skin).
- Dermis: The layer beneath the epidermis, containing blood vessels, nerves, and hair follicles.
- Hypodermis (Subcutaneous layer): The deepest layer, primarily composed of fat tissue.
The stratum lucidum, a thin, transparent layer, is unique to the thick skin found on the palms and soles. Its presence is due to the increased thickness and keratinization required for protection in these high-friction areas. This layer is characterized by the presence of eleidin, a protein precursor to keratin. Other layers, such as the stratum corneum (the outermost layer of the epidermis), are present in both thick and thin skin. However, the thickness of the stratum corneum varies greatly between thick and thin skin types.
While other layers might be more prominent or thicker in certain skin areas, the stratum lucidum's existence is exclusive to the thicker skin on palms and soles. References supporting the presence of the stratum lucidum in thick skin only include: information from the StatPearls article on the Epidermis ("...only in the skin of palms and soles"), and Chegg's solved question ("Which layer is seen only in thick skin? Stratum lucidum...").
