extracellulare

Extracellulare, often rendered as extracellular in English, refers to the environment outside cells within tissues and organisms. It includes the extracellular fluid that bathes cells and the extracellular matrix that provides structural support and biochemical cues. This compartment is distinct from the intracellular milieu, which lies within cell membranes.

Extracellular fluid comprises about one third of body water in humans and includes interstitial fluid, plasma, and transcellular fluids such as cerebrospinal fluid and synovial fluid. It serves as the medium for nutrient delivery, gas exchange, and waste removal between blood and cells. The composition and volume of the extracellular fluid are tightly regulated by organs such as the kidneys and hormones.

The extracellular matrix is a network of proteins and polysaccharides that fills the space between cells. Major components include collagen, elastin, laminin, fibronectin, and proteoglycans. The ECM determines tissue mechanics, guides cell migration, and modulates signaling through receptors such as integrins. ECM remodeling by enzymes like metalloproteinases plays a key role in development and disease.

Cells interact with the extracellular milieu through receptors, channels, and adhesion molecules, enabling communication, proliferation, and differentiation. The extracellular environment also participates in gradients of signaling molecules and mechanical cues that influence cell behavior. Abnormalities in extracellular composition or remodeling are linked to fibrosis, edema, cancer invasion, and metabolic disorders.