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.
The epidermis is the top, outer layer of the skin. It contains three main types of cells:
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. The basal cells sit on a very thin layer of tissue (the basement membrane) that separates the epidermis from the rest of the body.
Melanocytes – These cells sit between the basal cells and produce a dark pigment called melanin that gives skin its colour. When skin is exposed to ultraviolet (UV) radiation, melanocytes make melanin to try to protect the skin from getting burnt. Melanocytes are also found in non-cancerous spots on the skin called moles or naevi.
This layer of the skin sits below the epidermis. The dermis is made up of fibrous tissue and 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.
This information is reviewed by
This information was last reviewed in December 2021 by the following expert content reviewers: A/Prof Stephen Shumack, Dermatologist, Royal North Shore Hospital and The University of Sydney, NSW; Dr Margaret Chua, Radiation Oncologist, Head of Radiation Oncology, Skin and Melanoma, Peter MacCallum Cancer Centre, VIC; John Clements, Consumer; Aoife Conway, Skin Lead and Radiation Oncology Nurse, GenesisCare, Mater Hospital, NSW; Sandra Donaldson, 13 11 20 Consultant, Cancer Council WA; Kath Lockier, Consumer; Dr Isabel Gonzalez Matheus, Plastic and Reconstructive Surgery, Principal House Officer, Princess Alexandra Hospital, QLD; A/Prof Andrew Miller, Dermatologist, Canberra Hospital, ACT; Dr Helena Rosengren, Chair Research Committee, Skin Cancer College of Australasia, and Medical Director, Skin Repair Skin Cancer Clinic, QLD; Dr Michael Wagels, Staff Specialist Plastic and Reconstructive Surgeon, Princess Alexandra Hospital and Surgical Treatment and Rehabilitation Service, and Senior Lecturer, The University of Queensland, QLD; David Woods,