What is the primary function of fibroblasts during the maturation phase of wound healing?

• During the maturation phase of wound healing, fibroblasts play a key role in producing and remodeling the collagen matrix, which increases the wound’s tensile strength. Collagen fibers are reorganized from a random to a parallel alignment, and excess collagen is broken down to improve the functional and structural integrity of the repaired tissue. This phase can last for months to years, depending on the wound.

  Rationale for correct answer:
  C. Producing and remodeling the collagen matrix to increase tensile strength: Fibroblasts are responsible for ongoing collagen production and remodeling, which gradually restores the wound’s structural stability and reduces scar thickness.

  Rationale for incorrect answers:
  A. Clearing the wound of pathogens and dead cells: This is primarily the role of neutrophils and macrophages during the inflammatory phase.
  B. Forming a fibrin clot to stop bleeding: This is the function of platelets during the hemostasis phase.
  D. Creating new blood vessels to supply oxygen and nutrients: This occurs during angiogenesis in the proliferative phase, not during maturation.

  Take home points

• The maturation phase focuses on collagen remodeling and increased tensile strength.
• Fibroblasts remain active long after the wound has closed to optimize scar quality.
• Full tensile strength is never completely restored—healed wounds typically regain about 80% of their original strength.

During the inflammatory phase of wound healing, the body responds to injury by initiating immune and vascular processes to prevent infection and prepare the wound for tissue repair. Neutrophils are the first phagocytic cells to arrive, removing debris and bacteria. Local vasodilation increases blood flow, platelets release growth factors and cytokines to recruit immune cells, and increased vascular permeability allows plasma proteins and leukocytes to enter the wound site. Fibroblast migration and collagen synthesis occur later in the proliferative phase, not during inflammation.

Rationale for correct answers:
A. Neutrophils are the first phagocytic cells to arrive: Neutrophils infiltrate the wound within hours, removing pathogens and damaged tissue.
B. Vasodilation of local blood vessels: Mediated by histamine, prostaglandins, and nitric oxide, vasodilation increases delivery of immune cells and nutrients.
C. Platelets release growth factors and cytokines: These signals initiate inflammation and recruit additional immune cells to the wound.
E. Increased vascular permeability: This allows immune cells and plasma proteins to leave the bloodstream and enter the wound area for defense and repair preparation.

Rationale for incorrect answer:
D. Fibroblasts migrate into the wound to begin collagen synthesis: This is a hallmark of the proliferative phase, not the inflammatory phase.

Take home points

• Inflammation involves immune cell recruitment, vasodilation, and increased permeability.
• Platelets not only form clots but also signal immune and repair processes.
• Fibroblast-driven collagen synthesis occurs later, after the wound is cleaned and prepared.