The extracellular matrix (spaces) of the dermis consist out of approximately 85% collagen. Collagen is a protein that is composed of a large proportion of glycine (33%), proline (6-12%) and hydroxyproline (10-16%). It is the most abundant protein in the human body and takes over 70% of the dry weight of the dermis. In the human body 20 different collagen types are known. Approximately 80% of dermal collagen are to associate with the collagen type 1. Joints, cartilage and bone are build up mainly of collagen type 1.

The change of collagen determines the composition and structure of the dermis, on one hand it is conducted by the synthesis, on the other controlled by enzymatic degradation. Collagen is synthesized by fibroblasts in the dermis. Specific collagen fibers are responsible for the formation of collagen, these enzymes are a Matrixmetallproteinasen (MMP). The activity of Collagenases is recovered by the tissue inhibitors of metalloproteinases (tissue inhibitors of metalloproteinases engl. (TIMP)). The stability of the collagen fibers is thus determined by the balance of MMP and TIMP. Decreases the collagen with age, it comes to wrinkles in the skin.