It is made up of all the parts without specific functions of the organ - for example, connective tissue, blood vessels, ducts, etc.

The other part, the parenchyma, consists of the cells that perform the function of the tissue or organ.

Stromal tissue falls into the "functional" class that contributes to the body's support and movement.

The function of connective tissue proper is to secure the parenchymal tissue, including blood vessels and nerves of the stroma, and to construct organs and spread mechanical tension to reduce localised stress.

Extracellular matrix is primarily composed of ground substance - a porous, hydrated gel, made mainly from proteoglycan aggregates - and connective tissue fibers.