Abstract
<jats:p>Proportional organ growth requires tissue-level control of cell behavior. Yet the cues that adapt growth rates, especially after organ injury, remain unclear. Here, we uncover that developing organs are robust to extensive damage, triggering injury-specific mechanisms sufficient to override genetically-encoded size defects. Using precision microsurgery in developing zebrafish pectoral fins, we find that injury drives growth asynchronously across tissues and fin axes, by increasing proliferation and extracellular spacing. Growth compensation scales with the amount of tissue lost, restoring size and structure without compromising developmental timing. A feedback-control model captures these dynamics, suggesting that growth rates are regulated toward an organ-specific target area. At the molecular scale, injury signals bypass developmentally-regulated BMP gradient scaling. Injury instead activates de novo BMP signaling, which supports growth adaptation and rescues wildtype fin size in developmentally small mutants. Our findings identify an injury-dependent compensatory growth mechanism that resets developmental organ size, ensuring functional organ recovery.</jats:p>