ABSTRACT
The extracellular matrix is the natural environment in which the cells of multicellular organisms are embedded. Both in vivo as well as in vitro their constituent molecules modulate cell adhesion, spreading, growth, morphology, differentiation, and life span. In cell culture work, it is a common observation that cells adhere differently to glass, plastic, or other surfaces, and thus an understanding of how matrix factors influence cellular behavior is also of direct relevance in many clinical disciplines like surgery and prosthetics. Therefore, it is not surprising that the interest in the anatomy and function of the extracellular matrix is nearly as old as the cell concept itself. (For short reviews on the early history and the molecular oriented era, see References 1 and 2). Due to the development of many histological stains, the specific glycosylation of the “fundamental substance” was an early observation. Meanwhile, many molecules located specifically within the extracellular matrix have been characterized. Quantitatively, the majority of them belong to the classes of collagens, proteoglycans, and glycosaminoglycans, but also several other glycoproteins with different spatial and temporal distributions have been found. In order to perform their special tasks, they must be organized in a defined but presently only weakly understood meshwork.
