Many cells secrete materials into the regions which are outside the cellular membrane.
These materials form what is called the extracellular matrix in eukaryotic cells. This matrix forms structures range from anything from the framework of tendons and bones to the cell walls in plants. This matrix's primary function is to support, but it also regulates cell division adhesion, and many other important tasks in cellular life. In animals, the main areas of interest are the collagens, which are the primary fibers of the structures, and the proteoglycans, which are the main components of the surrounding network. In plants, the cell walls are the primary means for study in chapter 8.