Living tissues are not just tightly packed cells. Much of a tissue's volume is made up of extracellular space.
This void is filled with a complex meshwork called the extracellular matrix.
The ECM is a dynamic, physiologically active component of all living tissues.
In addition to providing structural support for the cells embedded within a tissue, the extracellular matrix guides their division, growth, and development.
A few key ingredients of the ECM are water, fibrous proteins, and proteoglycans.
The main fibrous proteins that build the ECM are collagens, elastins, and laminins.