## Distinguishing Features of Wound Healing Phases ### Inflammatory Phase (0–3 days) - Hemostasis and fibrin clot formation - Neutrophil infiltration (peak at 24–48 hours) - Macrophage recruitment and debris clearance - Minimal collagen synthesis ### Proliferative Phase (3–21 days) - **Active collagen deposition** (Type III collagen predominates) - **Angiogenesis** (new capillary formation) - **Fibroblast proliferation** and migration - Epithelialization and wound contraction - Decreased inflammatory cell infiltrate ### Remodeling Phase (21 days–2 years) - Collagen cross-linking and maturation - Type III → Type I collagen conversion - Angiogenesis regression - Scar formation and tensile strength gain **Key Point:** The proliferative phase is uniquely characterized by the **simultaneous occurrence of collagen synthesis, angiogenesis, and fibroblast activity**—these three features together form the hallmark discriminator from the inflammatory phase, which is dominated by cellular cleanup and hemostasis. **High-Yield:** On histology, the proliferative phase shows a **granulation tissue** appearance: new blood vessels, fibroblasts in a loose collagen matrix, and minimal inflammatory cells. This is pathognomonic and distinct from the fibrin-rich, cell-packed inflammatory phase. **Clinical Pearl:** Clinically, the proliferative phase corresponds to the period when a wound gains tensile strength (roughly 5% by day 7, 20% by day 14). Failure to enter this phase (e.g., in chronic wounds) results in persistent inflammation and poor healing.
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