What is the most abundant component of the extracellular matrix (ECM)?

Collagen is recognized as the most abundant component of the extracellular matrix (ECM) due to its crucial role in providing structural support and strength to tissues. Collagen fibers are infused throughout various types of tissues, including skin, bone, cartilage, and tendons, contributing to their tensile strength and integrity. There are multiple types of collagen, each serving specific functions and presenting distinct distribution patterns within different tissues, which highlights its significance in ECM composition.

While proteoglycans, aggrecan, and hyaluronan play important roles in the ECM, they do not match the abundance of collagen. Proteoglycans, which are made up of a core protein and glycosaminoglycan (GAG) chains, help to retain water and provide cushioning. Aggrecan is a specific type of proteoglycan found primarily in cartilage, involved in the compressive resistance of cartilage tissue. Hyaluronan, a large GAG, contributes to the viscoelastic properties of tissues and is significant in maintaining hydration and cellular signaling, but it is present in lesser amounts compared to collagen.

Understanding the hierarchy and roles of these components enhances our comprehension of tissue structure and function, emphasizing collagen's foundational role in the extracellular matrix.