Cross-section illustration of skin with the epidermis on the surface, made up of layers of keratinocytes, the dermis in which are found the structures of the skin such as the hair follicle, the sebaceous gland (yellow, next to the follicle), the arrector pili muscle, the sweat gland (purple, on the right), the blood vessels, as well as the free nerve endings (yellow), then the hypodermis made up of adipose cells (yellow).