What is the outermost cell layer of the epidermis called?

The outermost cell layer of the epidermis is the stratum corneum. This layer consists of dead skin cells that are continuously shed and replaced by new cells from the underlying layers of the epidermis. The primary function of the stratum corneum is to provide a protective barrier against environmental factors such as pathogens, chemicals, and physical stresses, as well as to prevent water loss from the body, which helps maintain hydration levels.

In contrast, the percutaneous layer refers to the portion of the skin that absorbs substances, which is not a specific layer of the epidermis. The dermis lies beneath the epidermis and contains connective tissue, blood vessels, and nerve endings, making it part of the skin but not the outermost layer. Subcutaneous tissue is the layer of fat and connective tissue located below the dermis that helps insulate the body and absorbs shock, but again, it is not part of the epidermis. Therefore, the stratum corneum is the correct answer as it accurately identifies the outermost layer of the epidermis, characterized by its role in providing the first line of defense for the body.