Which epidermal layer contains basal cells?

• A. Stratum granulosum
• B. Stratum spinosum
• C. Basal cells
• D. Stratum corneum

Answer: (C)

Basal cells live in the deepest part of the epidermis, the basal layer (stratum basale). This layer sits on the basement membrane and houses the stem-like keratinocytes that continually divide to renew the epidermis. As these cells divide, their offspring migrate upward through the layers, becoming more differentiated as they move toward the surface.

The other layers are composed of cells at later stages of differentiation: the granulosum contains keratinocytes with granules; the spinosum has living keratinocytes connected by desmosomes that give a spiny appearance; the corneum is made up of dead, keratin-filled cells. Because basal cells are specifically located in the basal layer, the choice that mentions basal cells best identifies the layer in question.