Representative confocal images of the tissues adjacent to the pancreas of control siblings and npas4l−/− Tg(ins:Flag-NTR) zebrafish larvae at 3 dpf after β-cell ablation by MTZ at 1–2 dpf, displaying cells expressing pancreatic endocrine cell markers Isl1 (A–B’), neurod1 (E–F’), pdx1 (I–J’), mnx1 (M–N’), pcsk1 (Q–R’), and ascl1b (U–V’) in green, and ectopic β-cells in red with immunostaining for insulin (except Q–R’ with the mCherry fluorescence driven by the insulin promoter). Arrowheads point to ectopic β-cells that express corresponding markers. Arrows point to β-cells that do not express ascl1b (V and V’). B’, F’, J’, N’, R’, and V’ are magnified from the areas indicated by the white dashed square in B, F, J, N, R, and V, respectively. Quantification of β-cells with or without corresponding marker expression in the ectopic location (C, G, K, O, S, and W) or in the pancreas (D, H, L, P, T, and X) per larva at 3 dpf. *p=0.0310, **p=0.0039, and ****p<0.0001 (Šidák’s multiple comparisons test); (C, D) n = 30 (control) and 31 (npas4l−/−); (G, H) n = 8 (control) and 8 (npas4l−/−); (K, L) n = 25 (control) and 24 (npas4l−/−); (O, P) n = 21 (control) and 23 (npas4l−/−); (S, T) n = 40 (control) and 32 (npas4l−/−); (W and X) n = 13 (control) and 13 (npas4l−/−). Data are represented as the mean ± SEM. Scale bars = 20 μm except B’, F’, J’, N’, R’, and V’ (10 μm). Anatomical axes: D (dorsal), V (ventral), A (anterior), and P (posterior).