Introductory Remarks

Abstract

Cytoskeleton, cell shape, cell migration, control of cell growth and differentiation, these are all subjects that to be fully understood today require a consideration of the extracellular matrix (ECM): its composition, its role in development, and its relation to the cell surface. The ECM is the structurally stable material that lies under epithelia and surrounds connective tissue cells, but the old concept of the ECM as an inert supporting material, created by the cells as a mere scaffolding on or in which to reside, is now bygone. Surely, collagens are sources of strength to the tissues, elastin and proteoglycans are essential to matrix resiliency, and the structural glycoproteins help to create tissue cohesiveness. But the cell, having produced these extracellular macromolecules, and spoken out in one way or another on the question of their assembly, does not then divorce itself of them. The cell continues to interact with its own ECM products, and with the ECM produced by other cells. At the cell surface, a structural and functional continuum seemingly is formed between the cell interior, the cell membrane, and the molecules of the matrix, so that the metabolism and fate of the cell, its shape, and many of its other properties are continuously related to and dependent on the composition and organization of the matrix.