[The spatial-temporal organization of the extracellular matrix]

Data on composition and structure of extracellular matrix (ECM) of different tissues and at different developmental stages are summarized. ECM secreted by cells is a complex supermolecular structure formed of polymerized collagen, elastin, proteoglycans, and structural glycoproteins. Its organization varies depending on tissue type or on location within the same tissue. Variation of ECM composition is determined by qualitative and quantitative differences in combination of its constituent components, as well as by microheterogeneity of these components. Permanent feed-back exists between cells and ECM. Morphological and functional relationships are established between basal membranes, ECM, pericellular matrix, and cytoskeleton. An important role in these relationships belongs to integrins, a family of transmembrane proteins specifically interacting with ECM components. ECM composition specifically changes during development and regeneration, correlating with differentiation and morphogenesis of corresponding tissues. Thus, ECM has a complex structure, is responsible, to a certain extent, for tissue specificity and for stage-specific differences between tissues, and can be regarded as a probable position information carrier, both in embryos and adult animals.