Which time frame best indicates macrophage-mediated clearance and beginning of granulation tissue after MI?

Which time frame best indicates macrophage-mediated clearance and beginning of granulation tissue after MI?

• A. 0-12 hours
• B. 3-7 days: macrophage-mediated clearance and granulation tissue begins
• C. 12-24 hours
• D. 1-2 weeks: granulation tissue

Answer: (B)

Macrophages take over during the transition from the early inflammatory stage to the proliferative repair stage, roughly around days 3 to 7 after a myocardial infarction. Right after injury, neutrophils dominate the response, cleaning debris in the first 0–2 days. As neutrophils wane, monocytes migrate in and differentiate into macrophages, which actively clear necrotic debris and secrete factors that recruit fibroblasts and new blood vessels. This sets the stage for granulation tissue, which begins to form within this same window (about day 3–7) and becomes more evident over the next week or two. By 1–2 weeks, granulation tissue is prominent, and later weeks lead to scar formation. So the timeframe that best fits macrophage-mediated clearance and the onset of granulation tissue is 3–7 days.

Macrophages take over during the transition from the early inflammatory stage to the proliferative repair stage, roughly around days 3 to 7 after a myocardial infarction. Right after injury, neutrophils dominate the response, cleaning debris in the first 0–2 days. As neutrophils wane, monocytes migrate in and differentiate into macrophages, which actively clear necrotic debris and secrete factors that recruit fibroblasts and new blood vessels. This sets the stage for granulation tissue, which begins to form within this same window (about day 3–7) and becomes more evident over the next week or two. By 1–2 weeks, granulation tissue is prominent, and later weeks lead to scar formation. So the timeframe that best fits macrophage-mediated clearance and the onset of granulation tissue is 3–7 days.