What is the function of interstitial fluid?

Interstitial fluid is the liquid which surrounds the cells in the body. The function of intestitial fluid is to carry substances between the blood and the tissue cells. Substances passing out of the blood capillaries eg food,oxygen, pass through the interstitial fluid to reach the body cells. Substances produced by the cells eg carbon dioxide waste, pass through the tissue fluid to enter the blood capillaries. See: http://en.wikipedia.org/wiki/Interstitial_fluid