<P> Extracellular fluid (ECF) denotes all body fluid outside the cells . Total body water in humans makes up between 45 to 75% of total body weight . About two thirds of this is intracellular fluid within cells, and one third is the extracellular fluid . The main component of the extracellular fluid is the interstitial fluid that bathes cells . </P> <P> Extracellular fluid is the internal environment of all multicellular animals, and in those animals with a blood circulatory system a proportion of this fluid is blood plasma . Plasma and interstitial fluid are the two compartments that make up at least 97% of the ECF . Lymph makes up a small percentage of the interstitial fluid . The remaining small portion of the ECF includes the transcellular fluid (about 2.5%). The ECF can also be seen as having two components--plasma and lymph as a delivery system, and interstitial fluid for water and solute exchange with the cells . </P>

Fluid located between the cells in tissues is called