<p><b>(</b>A-D) DHE fluorescence (red) indicates the presence of ROS. <i>nub-GFP</i> (green) marks the regenerating wing pouch. (A-B) Confocal slices of a <i>w</i><sup><i>1118</i></sup> regenerating disc through the debris field (A,A’) and the disc epithelium (B,B’). Asterisks mark cellular debris in the debris field and in a few folds in the epithelium. Arrow points to the position of the regenerating wing pouch. (C-D) Confocal slices of a <i>mol</i><sup><i>e02670</i></sup><i>/+</i> regenerating disc through the debris field (C,C’) and the regenerating epithelium (D,D’). Asterisk and arrow same as above. (E-F) Quantification of DHE fluorescence intensity in the debris fields of <i>w</i><sup><i>1118</i></sup> and <i>mol</i><sup><i>e02670</i></sup><i>/+</i> regenerating discs (E) and in the regenerating epithelia of <i>w</i><sup><i>1118</i></sup> and <i>mol</i><sup><i>e02670</i></sup><i>/+</i> regenerating discs and control undamaged discs (F). For R24, three independent experiments, for a total <i>w</i><sup><i>1118</i></sup> regenerating n = 12 discs, <i>mol</i><sup><i>e02670</i></sup><i>/+</i> regenerating n = 18 discs, <i>w</i><sup><i>1118</i></sup> undamaged n = 11 discs. For R48, three independent experiments for a total <i>w</i><sup><i>1118</i></sup> regenerating n = 30 discs, <i>mol</i><sup><i>e02670</i></sup><i>/+</i> regenerating n = 25 discs, <i>w</i><sup><i>1118</i></sup> undamaged n = 10 discs. (G,H) Quantification of GFP fluorescence from a <i>gstD-GFP</i> reporter for ROS-regulated transcription in regenerating <i>w</i><sup><i>1118</i></sup> and <i>mol</i><sup><i>e02670</i></sup><i>/+</i> discs. For R24, <i>w</i><sup><i>1118</i></sup> n = 12 discs, <i>mol</i><sup><i>e02670</i></sup><i>/+</i> n = 20 discs. For R48, <i>w</i><sup><i>1118</i></sup> n = 12 discs, <i>mol</i><sup><i>e02670</i></sup><i>/+</i> n = 10 discs. (I) Adult wing area in <i>w</i><sup><i>1118</i></sup> and <i>mol</i><sup><i>e02670</i></sup><i>/+</i> male and female wings from undamaged discs and after disc regeneration. Three independent experiments. Undamaged: <i>w</i><sup><i>1118</i></sup> females n = 125 wings, <i>w</i><sup><i>1118</i></sup> males n = 132 wings, <i>mol</i><sup><i>e02670</i></sup><i>/+</i> females n = 82 wings, <i>mol</i><sup><i>e02670</i></sup><i>/+</i> males n = 73 wings. Regenerated: <i>w</i><sup><i>1118</i></sup> females n = 226 wings, <i>w</i><sup><i>1118</i></sup> males n = 134 wings, <i>mol</i><sup><i>e02670</i></sup><i>/+</i> females n = 128 wings, <i>mol</i><sup><i>e02670</i></sup><i>/+</i> males n = 133 wings. (J-O) Anti-Nub marks the regenerating wing primordium at R0, R24 and R48 in <i>w</i><sup><i>1118</i></sup> and <i>mol</i><sup><i>e02670</i></sup><i>/+</i> discs. (P) Quantification of the size of the regenerating wing primordium at R0, R24 and R48. R0 <i>w</i><sup><i>1118</i></sup> n = 26 and <i>mol</i><sup><i>e02670</i></sup><i>/+</i> n = 29, R24 <i>w</i><sup><i>1118</i></sup> n = 42 and <i>mol</i><sup><i>e02670</i></sup><i>/+</i> n = 41, R48 <i>w</i><sup><i>1118</i></sup> n = 29 and <i>mol</i><sup><i>e02670</i></sup><i>/+</i> n = 42. Scale bars are 100 μm. Error bars are SEM. **p<0.05, *p<0.005, ***p<0.0002, ****p<0.0001.</p