Extracellular matrix
From Wikinfo
In biology, extracellular matrix (ECM) is any material part of a tissue but not part of any cell. Extracellular matrix is the defining feature of connective tissue.
ECM can be made up of proteins such as collagen, fibrin and elastin; minerals such as hydroxyapatite; or fluids such as blood plasma. Given this diversity, it can serve any number of functions.
Adapted from the Wikipedia article, "Extracellular_matrix" [1], used under the GNU Free Documentation License

