Fig. 6. cnox-2+ cells in head-regenerating tips that have just traversed the cell cycle. (A-C) Head-regenerating tips oriented toward the top, showing increasing density of BrdU-labeled (green) and cnox-2+ (red) cells, ultimately surrounding the mouth opening at 44 hpa (B,C). (D-F) Confocal views of BrdU⁺/cnox-2⁺ apical cells (green/red), which appear as asymmetrical pairs (D), differentiating processes (E, arrow) or dividing i-cells (F). Hydra (Hv), BrdU-labeled before amputation, were fixed at 20 hpa (A,D,E), 32 hpa (F) and 44 hpa (B,C). Scale bars: 10 µm. mo, mouth opening.