Which epidermal layer is present only in thick skin and lies between the stratum granulosum and stratum corneum?

• A. Stratum lucidum
• B. Stratum basale
• C. Stratum spinosum
• D. Stratum granulosum

Answer: (A)

Thick skin has an extra translucent epidermal layer that sits between the stratum granulosum and the stratum corneum. This layer, present only in thick skin (not in thin skin), is the stratum lucidum. Its cells are flattened keratinocytes that have lost their nuclei and organelles and contain eleidin, a keratin precursor, giving the layer a clear appearance. The lucidum provides an additional barrier and helps resist friction and water loss in areas of high wear, like the palms and soles. The other layers—basale, spinosum, and granulosum—are found in both thick and thin skin, but none occupies the position between granulosum and corneum and is exclusive to thick skin.