The skin is the largest organ of the body. It acts as a barrier to protect the body from injury, control body temperature and prevent loss of body fluids.

The two main layers of the skin are the epidermis and dermis. Below these is a layer of fatty tissue.

Epidermis

This is the top, outer layer of the skin. It is made up of several cell types:

Squamous cells – These flat cells are packed tightly together to make up the top layer of skin. They form the thickest layer of the epidermis.

Basal cells – These block-like cells make up the lower layer of the epidermis. The body makes new basal cells all the time. As they age, they move up into the epidermis and flatten out to form squamous cells.

Melanocytes – These cells sit between the basal cells and produce

a dark pigment called melanin, the substance that gives skin its colour. When skin is damaged by ultraviolet (UV) radiation, melanocytes make extra melanin. Melanocytes are also found in non-cancerous spots on the skin called moles or naevi

Dermis

This layer of the skin sits below the epidermis. The dermis contains the roots of hairs (follicles), sweat glands, blood vessels, lymph vessels and nerves. All of these are held in place by collagen and elastin, the proteins that give skin its strength and elasticity.