Chapter 2 The Extracellular Matrix: A Dynamic Component of the Developing Embryo

Abstract

This chapter discusses the studies of some molecular characteristics of extracellular matrix and temporal correlations with other developmental events. In this manner, some aspects of the cellular environments during embryonic development are explained in this chapter. By concentrating on the early stages of embryonic development, an attempt is made to elucidate the matrix synthesis at the time the embryo is still histologically simple, yet when major interactions are occurring. Mature tissues and organs are functionally integrated units that consist of both cellular and extracellular elements. Extracellular regions contain a variety of substances, including macromolecules, water, and ions. Collectively these substituents form the extracellular matrix. Extracellular matrices exhibit a great deal of quantitative variation among different tissues. The macromolecules of the extracellular matrix, for example, glycosaminoglycans, collagen, and glycoproteins, are all cell products. Macromolecular composition to a large extent determines the degree of hydration, ionic composition, permeability, and mechanical properties of different extracellular matrices. Chronological changes in macromolecules differ among different matrices, but there is no evidence that each different developing tissue synthesizes with unique embryonic variants of collagen or glycosaminoglycan polysaccharide.