What best describes the epidermis?

The epidermis is best described as the outer layer of the skin, and it is characterized by its lack of blood vessels and nerves. This protective layer is critical for safeguarding the underlying tissues from environmental threats such as pathogens, chemicals, and physical injuries. The cells in the epidermis are primarily made up of keratinocytes, which produce keratin, a protein that helps to waterproof and protect the skin. Due to the absence of blood vessels, the epidermis receives its nutrients through diffusion from the underlying dermis, which contains the necessary blood supply. This description highlights the epidermis's role in providing an initial barrier and its structural composition, making it distinct from other skin layers that contain blood vessels or connective tissues.