Structure and Properties of Ground Substances

SYNOPSIS. Studies of arthropods and other animals including man have revealed that the interstitium, cytoplasm, and nucleus each contain a matrix or ground substance composed of various biopolymers. The extracellular ground substance consists of chains of glycosaminoglycan molecules which may be linked with hyaluronate to form supramolecular complexes called proteoglycans. The cytoplasmic ground substance contains microtubules, microfilaments, microtrabeculae, and intermediate filaments, and constitutes a movable cytoskeleton. This framework interconnects the cell surface, the various organelles, and the nuclear envelope. The nuclear matrix consists of a peripheral pore complex lamina and an internal matrix. Glycophorin, fibronectin, and other proteins appear to provide specific linkages between the extracellular and cytoplasmic ground substance. The nuclear matrix has peripheral elements that appear to interact with the cytoskeleton at specific sites. Intimately associated with the ground substances is a dynamic matrix composed of water and counterions. The structure of the whole system, macromolecules, water, and ions, is being built up from basic laws and principles, enabling quantum mechanical descriptions to be extended to domains containing many interacting components.