A cell type involved in forming extracellular matrix and collagen fibers?

• A. Platelet
• B. Macrophage
• C. Neutrophil
• D. Fibroblast

Answer: (D)

Forming extracellular matrix and collagen fibers is the job of fibroblasts, the resident cells of connective tissue. Fibroblasts synthesize the protein precursors like procollagen, secrete them into the extracellular space, and organize them into collagen fibers that provide structural strength. They also produce other ECM components such as elastin and proteoglycans and regulate matrix remodeling. Platelets are mainly involved in clotting, while macrophages and neutrophils are immune cells that handle defense and inflammation. In short, fibroblasts are the cells that build the extracellular framework and collagen fibers.