Fig. 4. Rapid G₂ during regenerative outgrowth. (A-C) Representative sections of fins treated with BrdU for (A) 40 minutes, (B) 70 minutes, and (C) 140 minutes and stained for BrdU (red) and H3P (green). Double labeling appears yellow (arrowheads). Note the absence of double-labeled cells after 40 minutes, presence of some double-labeled cells after 70 minutes, and labeling of all H3P-positive cells with BrdU after 140 minutes. (D) Plot of the fraction of labeled mitoses over time. Each time point represents measurements ±s.d. from 40 sections obtained from three or four regenerates. Scale bars: 100 µm.