Which epidermal layer is the innermost actively dividing layer?

Which epidermal layer is the innermost actively dividing layer?

• A. Stratum Corneum
• B. Stratum Basale
• C. Stratum Lucidum
• D. Stratum Spinosum

Answer: (B)

The layer at the base of the epidermis is where active cell division happens. It sits directly on the basement membrane and contains basal keratinocytes with stem-cell–like properties. These cells constantly divide, producing one daughter cell that stays in the basal layer and another that moves upward to differentiate through the other epidermal layers. The cells in the upper layers (spinosum, granulosum, lucidum in thick skin, and corneum) are progressively more differentiated and eventually become non-viable, dead cells. Because of this ongoing mitosis and renewal right at the base, the innermost actively dividing layer is the basal layer.

The layer at the base of the epidermis is where active cell division happens. It sits directly on the basement membrane and contains basal keratinocytes with stem-cell–like properties. These cells constantly divide, producing one daughter cell that stays in the basal layer and another that moves upward to differentiate through the other epidermal layers. The cells in the upper layers (spinosum, granulosum, lucidum in thick skin, and corneum) are progressively more differentiated and eventually become non-viable, dead cells. Because of this ongoing mitosis and renewal right at the base, the innermost actively dividing layer is the basal layer.