Keratinization is most active in which epidermal layer?

Keratinization is most active in which epidermal layer?

• A. Stratum lucidum
• B. Stratum granulosum
• C. Stratum corneum
• D. Stratum germinativum

Answer: (B)

Keratinization (cornification) is most active as keratinocytes move upward and begin to mature into the barrier-forming cells. The stratum granulosum is the hotspot for this process: cells here stop dividing, flatten, and fill with keratin while keratohyalin granules help knit the keratin filaments together. Lamellar bodies release lipids that create the waterproof barrier, so these cells are undergoing the key biochemical changes that convert living cells into the tough, flattened corneocytes. By the time cells reach the stratum corneum, keratinization is essentially complete—the cells are dead and filled with keratin, forming the outer protective layer. The deepest layer (where new cells are produced) is where keratinization starts, but the peak activity happens in the granular layer. Stratum lucidum is a transitional layer seen in thick skin and isn’t the primary site of ongoing keratinization.

Keratinization (cornification) is most active as keratinocytes move upward and begin to mature into the barrier-forming cells. The stratum granulosum is the hotspot for this process: cells here stop dividing, flatten, and fill with keratin while keratohyalin granules help knit the keratin filaments together. Lamellar bodies release lipids that create the waterproof barrier, so these cells are undergoing the key biochemical changes that convert living cells into the tough, flattened corneocytes. By the time cells reach the stratum corneum, keratinization is essentially complete—the cells are dead and filled with keratin, forming the outer protective layer. The deepest layer (where new cells are produced) is where keratinization starts, but the peak activity happens in the granular layer. Stratum lucidum is a transitional layer seen in thick skin and isn’t the primary site of ongoing keratinization.