What is the primary identifying feature of the subcutaneous layer of skin?

The primary identifying feature of the subcutaneous layer of skin is the presence of adipose tissue. This layer, also known as the hypodermis, serves as an insulating layer that helps to conserve body heat, provides cushioning to protect underlying structures, and serves as an energy reserve. Adipose tissue consists of fat cells that store energy and contribute to the overall structure and function of this layer.

While blood vessels, hair follicles, and nerve endings are present in the skin, they are primarily located in the epidermis and dermis, not in the subcutaneous layer. The presence of adipose tissue is what distinctly characterizes this layer, differentiating it from the other layers of the skin.