interstitiën

Interstitiën are the plural Dutch term for interstitium, the network of spaces located between cells within tissues. The interstitium contains interstitial fluid, components of the extracellular matrix and various resident or transient cells. It is distinct from the intracellular compartment and from luminal spaces such as blood vessels or organ cavities.

These spaces occur throughout the body, in connective tissue, organs and supporting structures. The interstitium includes collagen and elastin fibers, proteoglycans and other extracellular matrix elements, as well as fluid that surrounds cells. It houses cells such as fibroblasts, macrophages and mast cells and is routinely traversed by capillaries and lymphatic vessels that drain interstitial fluid.

Physiological roles include providing mechanical support to tissues, facilitating diffusion of nutrients, gases and signaling molecules, and enabling immune surveillance. It acts as a communication interface between circulating blood and tissue cells and helps shape tissue responses to injury and inflammation.

Pathological changes of the interstitium are central to many diseases. Edema refers to excess interstitial fluid accumulation, while interstitial fibrosis involves excessive deposition of extracellular matrix, reducing tissue compliance. The interstitium is a key feature in interstitial lung disease, chronic kidney disease and liver fibrosis. In the late 2010s some researchers described the interstitium as a potential new organ, a claim that sparked debate and remains controversial in the absence of universally accepted evidence.