Thick skin contains a clear layer packed with eleidin called the stratum
A spinosum
B lucidum
C granulosum
D corneum
The correct answer and explanation is:
The correct answer is: B) lucidum
Explanation:
Thick skin, such as the skin on the palms of the hands and the soles of the feet, contains several distinct layers in the epidermis. One unique characteristic of thick skin is the presence of a clear, translucent layer called the stratum lucidum.
- Stratum lucidum is a thin, clear layer of dead skin cells found only in thick skin.
- This layer is packed with eleidin, a clear, lipid-rich protein that is a transformed form of keratohyalin granules.
- Eleidin contributes to the transparency and provides a barrier that is both tough and flexible.
- The stratum lucidum lies just beneath the stratum corneum (the outermost layer) and above the stratum granulosum.
- This layer helps protect thick skin from friction and shear forces that are common on palms and soles.
Other layers for context:
- Stratum spinosum: Known as the “spiny layer,” it contains living keratinocytes that are connected by desmosomes. It provides strength and flexibility.
- Stratum granulosum: The “granular layer” where keratinocytes start to die and accumulate keratohyalin granules, which eventually transform into eleidin.
- Stratum corneum: The outermost layer composed of dead, flattened keratinocytes fully keratinized to provide a tough protective barrier.
Summary:
The stratum lucidum is a specialized layer in thick skin characterized by the presence of eleidin. This clear layer is crucial for the durability and resilience of skin exposed to heavy abrasion and mechanical stress, such as the palms and soles. It is absent in thin skin, which covers most of the body.