Final answer:
The matrix is composed of cells, ground substance, and protein fibers, which are all essential components of connective tissues in the body.
Step-by-step explanation:
The matrix is composed of cells, ground substance, and protein fibers. Connective tissues, which contain the matrix, are characterized by these components. The fibroblasts, which are the principal cells in connective tissues, create the protein fibers embedded within the ground substance. This ground substance is primarily made up of polysaccharides like hyaluronic acid and proteins that combine to form proteoglycans. The proteoglycans trap moisture, contributing to the clear, viscous, and colorless nature of the ground substance. Overall, the matrix in connective tissues gives the tissue its density and is essential for providing strength, elasticity, and protection to various structures in the body.