EXTRACELLULAR-MATRIX .3. EVOLUTION OF THE EXTRACELLULAR-MATRIX IN INVERTEBRATES

Invertebrates comprise about 95% of animal species, yet most studies o f extracellular matrices have centered on vertebrates. Comparative stu dies of invertebrates will enhance comprehension of evolutionary proce sses and appreciation of the diversity of extracellular matrices. More over, new functions and new structures will be revealed over a wide ra nge of organismic needs. Another important perspective is that several invertebrate species have provided insight into developmental process es, and those processes often have direct relevance to vertebrate deve lopment. Thus, studies of fruit flies, nematodes, and sea urchins have revealed common features of cell biology, embryonic development, and matrix properties that pertain throughout the animal kingdom. The adva ntages of invertebrates arc their rapid rates of embryonic development , their amenability to genetic manipulation, availability of innumerab le mutants, and their ease of study in the laboratory. Extracellular m atrices themselves are readily compared. Invertebrates display a wide diversity of such matrices, at the levels of both tissue architecture and molecular anatomy. Knowledge of that diversity leads to an appreci ation of evolutionary variety and eventually to comprehension of the o rganization of extracellular matrices and of the properties of their c onstituent macromolecules. The expanding knowledge of unique matrix mo lecules from invertebrates also has economic potential and is beginnin g to provide new materials for biotechnology.