Dermis

The intermediate layer of the skin, located between the epidermis and hypodermis, 1 to 4 mm thick. Mainly composed of collagen (70 to 80% of its dry weight), elastin and hyaluronic acid, synthesised by fibroblasts. It gives skin its mechanical resistance, elasticity and water-retaining capacity. Also contains blood vessels, nerve endings, hair follicles and sweat and sebaceous glands. Its progressive degradation with age, accelerated by sun and tobacco, causes wrinkles and loss of skin elasticity.