In wound healing, the process of contraction is mediated primarily by which cell type, and during which phase does it predominantly occur?

• A Macrophages; inflammatory phase (days 1–4)
• B Fibroblasts; haemostatic phase (within 24 hours)
• C Keratinocytes; maturation/remodelling phase (months 1–2)
• D Myofibroblasts; proliferative/remodelling phase (days 4–21) ✓

Explanation

Wound contraction is mediated by myofibroblasts — fibroblasts that have differentiated under TGF-β1 stimulation and express alpha-smooth muscle actin (α-SMA). This process begins during the proliferative phase (approximately day 4 onwards) and is responsible for reducing wound size by up to 60–80% in open wounds. Macrophages orchestrate inflammation and growth factor release. Keratinocytes drive re-epithelialisation by migration and proliferation. Fibroblasts in the haemostatic phase are not yet active. Myofibroblast contraction is pathologically exaggerated in hypertrophic scars and contractures.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

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