Final answer:
The extracellular matrix is composed of protein fibers and a gel-like ground substance made of proteoglycans, which consists of a protein core and polysaccharide branches that retain moisture, giving the ground substance viscous and clear qualities.
Step-by-step explanation:
The extracellular matrix of connective tissue is comprised of protein fibers and gel-like ground substance. Within the matrix, fibroblasts secrete the ground substance, which is primarily made of polysaccharides like hyaluronic acid and various proteins that combine to form proteoglycans. This proteoglycan has a core of protein with branches of polysaccharides, creating a network that helps to retain moisture and give the ground substance its viscous and clear qualities. Collagen fibers, which offer great tensile strength and resistance to stretching, are also embedded in this matrix, along with elastic fibers and reticular fibers, providing resilience and structural support to the body's tissues.