The extracellular matrix (ECM) is part of the connective tissue and provides support in the animal cell. Therefore the extracellular matrix is situated in the interstitial matrix and includes the basement membrane. Mainly fibroblasts are the components of the extracellular matrix. Fibrous proteins that are of importance in the buildup of the extracellular matrix are elastin, collagen, laminin, vitronectin and fibronectin. Additionally polysaccharides like hyaluronic acid fill the intercellular space with a gel-like material. In tissue sections the space these proteins and substances occupy therefore appears to be empty.
Other components of the extracellular matrix are proteoglycans which are hydrophil and thereby keep the interstitial space hydrated, which is one of the functions of the extracellular matrix. Other functions of the extracellular matrix are to strengthen, stabilize and provide elasticity. This function is achieved by the extracellular matrix allowing adhesion and attachment of cells to the protein laminin for instance, via their cytoskeletal protein structure, for example via actin structures.
Additionally the extracellular matrix plays a role in signal transduction and in the storage and supply of nutrients and hormones. Due to these functions the extracellular matrix plays an important role in the repair of damages to tissues. Interestingly, in human fetuses the extracellular matrix has been indicated in the development, working in concert with stem cells.