The largest quantities of keratin are found in the epidermal layer called the stratum:

• A. corneum
• B. granulosum
• C. basale
• D. spinosum

Answer: (A)

Verified step by step guidance

1. Understand the structure of the epidermis, which consists of multiple layers: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum (only in thick skin), and stratum corneum.
2. Learn the function of keratin, a protein that provides strength and waterproofing to the skin, and is produced by keratinocytes as they mature and move upward through the epidermal layers.
3. Recognize that keratinocytes begin producing keratin in the stratum granulosum, but the largest quantities of keratin are found in the stratum corneum, the outermost layer of the epidermis.
4. Understand that the stratum corneum is composed of dead keratinized cells, which form a tough, protective barrier against environmental damage and water loss.
5. Review the options provided and identify that the stratum corneum is the correct answer based on its role as the layer with the highest concentration of keratin.