The layer known as the germinative or basal layer is which?

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

Answer: (A)

The germinative or basal layer is the deepest portion of the epidermis, resting on the basement membrane. Its cells are primarily basal keratinocytes that are actively dividing, continuously replenishing the epidermis as cells are shed from the surface. This layer also houses melanocytes, which produce pigment, and Merkel cells, which contribute to tactile sensation. Because these cells are mitotically active, new keratinocytes are pushed upward from this layer to form the layers above—spinosum, granulosum, and eventually the cornified layer. The layers above differ in structure and function: the spinous layer contains keratinocytes connected by desmosomes giving a spiny appearance; the granular layer has keratohyalin granules involved in keratinization; and the cornified layer consists of dead, flattened cells that form the protective outer barrier. Therefore, the germinative or basal layer corresponds to the Stratum Basale.