Final answer:
Glycoproteins, proteoglycans, polysaccharides, and water collectively constitute the gel-like "ground substance" of the extracellular matrix.
Step-by-step explanation:
The ground substance is a vital component of the extracellular matrix (ECM), providing a gel-like consistency to the matrix. It consists of glycoproteins, proteoglycans, polysaccharides, and water.
Glycoproteins, such as fibronectin and laminin, contribute to the structural integrity of the ECM. Proteoglycans are molecules composed of a core protein and long chains of carbohydrates, imparting viscosity to the ground substance. Polysaccharides, in the form of long sugar chains, further contribute to the gel-like nature of the ground substance.
Water, filling the spaces between the molecules, gives the ground substance its characteristic fluidity, facilitating cell movement and providing a medium for various biochemical processes within the ECM.