Saylor.org's Cell Biology/The Extracellular Matrix (ECM)
Different types of cells produce and secrete different molecules that can alter their external environment. An environment that has been altered in this way is known as the extracellular matrix. The matrix’s main purpose is to form an ordered network for physical support, but it also plays a role in signaling, immunity, and wound healing. There are five main classes of ECM molecules; all ECMs are comprised of some combination of these five types.