Massachusetts State Board Esthetics Practice Exam

Which layer contains cells that are continuously undergoing mitosis?

1. Stratum germinativum

2. Stratum spinosum

3. Stratum granulosum

4. Stratum corneum

The correct answer is: Stratum germinativum

The stratum germinativum, also known as the basal layer, is the deepest layer of the epidermis and is primarily responsible for the production of new skin cells. Cells in this layer are continuously undergoing mitosis, which allows for the regeneration of the skin. This process is essential for maintaining the skin's integrity and providing a constant supply of new cells that will eventually move up through the other layers of the epidermis. As new cells are generated in the stratum germinativum, older cells above them are pushed toward the surface, where they undergo a process of keratinization. This keeps the skin replenished and is vital for healing and protecting the body from environmental factors. In contrast, the stratum spinosum contains cells that begin to flatten and start the keratinization process but are not actively dividing like those in the stratum germinativum. The stratum granulosum is where cells begin to lose their nuclei and become more keratinized, while the stratum corneum is made up of dead, keratinized cells that form the outermost protective layer of the skin. These layers play essential roles in the overall function of the skin, but only the stratum germinativum is