Maximum amount of fibroblasts occurs how long after injury?

• A. 24 hours
• B. 1 week
• C. 2 weeks
• D. 6 weeks

Answer: (B)

Fibroblasts peak during the proliferative phase of wound healing, when the body is building new connective tissue. After injury, growth factors recruit fibroblasts to migrate into the wound and start synthesizing collagen and other extracellular matrix, forming granulation tissue. This activity reaches its highest level around one week after injury, providing the bulk of the new tissue that will later be remodeled. By about two weeks, fibroblast numbers begin to decline as remodeling progresses and collagen becomes more crosslinked. Early on, within the first day, inflammatory cells dominate rather than fibroblasts, so the peak isn’t at 24 hours, and later than one week the fibroblast activity starts to wane.