During the fibrosis cycle, connective tissue shrinkage occurs after which stage?

• A. Vascular support system increase
• B. Increased collagen synthesis
• C. Macrophage activation
• D. Myofibroblast infiltration and activation

Answer: (D)

Myofibroblast infiltration and activation drive the contraction of scar tissue. After injury, inflammatory signals recruit macrophages and stimulate fibroblasts to produce collagen, laying down the extracellular matrix. As the wound progresses, fibroblasts differentiate into myofibroblasts, which express contractile proteins and pull on the surrounding matrix. This contractile activity pulls the wound edges together and causes connective tissue shrinkage. Vascular changes and early macrophage activation occur in the inflammatory phase, and increased collagen synthesis occurs as part of matrix deposition, but the actual shrinkage is due to myofibroblast activation and contraction.