What is the main characteristic of the epidermis?

The main characteristic of the epidermis is that it serves as a barrier to pathogens. This outermost layer of skin provides a critical protective function for the body, preventing the entry of bacteria, viruses, and other harmful substances. The epidermis is primarily composed of keratinocytes, which produce keratin, a protein that strengthens the skin and adds to its barrier properties.

Additionally, the epidermis is avascular, meaning it does not contain blood vessels, and instead relies on the underlying dermis for nutrients and oxygen. As such, it is not the innermost layer of skin; rather, it is the outermost. The epidermis is also not filled with fat cells, which are primarily found in the subcutaneous layer beneath the skin. This reinforces the idea that the primary role of the epidermis is to protect the body from external threats.