Which layer of skin contains keratinocytes?

The epidermis is the outermost layer of skin and is primarily composed of keratinocytes, which are cells that produce keratin—a critical protein that helps protect the skin and underlying tissues from damage, infection, and water loss. Keratinocytes undergo a process of maturation as they move from the lower layers of the epidermis to the surface, where they eventually die and form a protective barrier.

The dermis, which lies beneath the epidermis, contains connective tissues, blood vessels, and various skin cells but does not primarily consist of keratinocytes. The subcutaneous layer, also known as the hypodermis, is primarily made up of fat and connective tissue and serves as insulation and a cushion for the body. Muscle tissue is found deeper in the body and is not part of the skin, making the epidermis the correct answer for the presence of keratinocytes.