Aesthetic applications of intense pulsed light

Abstract

The skin is composed of three layers: epidermis, dermis and subcutaneous tissue. The thickness of the layers varies with different anatomical regions. The epidermis is thickest on the palm and soles, and very thin on the eyelids, while the dermis is thickest on the back. Keratinocytes are the main component of the epidermis. Melanocytes are the cells located in the epidermis whose function it is to produce pigment. The ratio is about one in every ten basal keratinocytes. Differences in skin color according to race are explained by the number of melanosomes. Langerhans cells represent 3-5% of the cells of the stratum spinosum where they are situated between the keratinocytes. The dermis consists of a supporting matrix (ground substances) in which polysaccharides and proteins act to produce proteoglycans. The protein fibers inside the dermis are represented by collagen, elastin and other components, such as fibrillin and microfibril proteins. The blood supply to the skin comes from the deep plexuses located at the fascia and subcutaneous level. With aging, there is a decrease in total collagen content in the skin, an increased amount of type III collagen, decreased number and diameter of elastin fibers, and a lack of interaction between water and surrounding molecules which contribute to the dry and wrinkled aspect. © Springer-Verlag London Limited 2011.