American Academy of Professional Coders (AAPC) Practice Exam

What type of cells primarily compose the stratum basale?

1. Squamous cells

2. Keratinocytes

3. Adipocytes

4. Melanocytes

The correct answer is: Keratinocytes

The stratum basale, also referred to as the basal layer, is the deepest layer of the epidermis and primarily consists of keratinocytes. These are the predominant cell type in this layer and are responsible for the production of keratin, a vital protein that contributes to the protective barrier of the skin. In the stratum basale, keratinocytes undergo mitosis, which leads to the continual regeneration of the skin. As new cells are produced in this layer, older cells are pushed upward through the various layers of the epidermis, ultimately leading to their maturation and death in the outermost layers. While the stratum basale also contains melanocytes, which are responsible for producing the pigment melanin, these are not the primary cell type within this layer. Adipocytes, or fat cells, are typically found in the subcutaneous layer rather than the epidermis and squamous cells do not comprise the stratum basale, as they are associated more with the outer layers of squamous epithelium in the skin. Understanding the function of keratinocytes and their prevalence in the stratum basale is crucial for recognizing how the skin maintains its structure and function.