Anatomy of the interstitial tissue.

Aspects on composition and function of the interstitial tissue have been given. The glycosaminoglycans of the interstitum have at physiological pH a net negative charge and are osmotically active. They restrict free diffussion through the interstitium. The ground substance phase can be further subdivided into a colloid-rich subphase and a colloid-poor subphase. The latter seems to constitute the true tissue fluid phase of the interstitium. The functional importance of the interstitium on exchange processes between the vascular and the cellular compartments is discussed. Changes in aggregation and hydration of the ground substance change the physico-chemical properties and the functional characteristics of the interstitium.