tcf7l2 is required for regulation of insulin expression and exocrine pancreas development. Analysis of insulin in control embryos (A) and in tcf7l2 exI/exI mutants (A’) by in situ hybridization. Lateral views of the pancreatic area are shown with the anterior side to the right. The expression of insulin is significantly reduced in the mutants. (B–B”) Analysis of pancreatic islet in tcf7l2 exI/exI mutant in Tg(ins:dsRed) background. 2D projections of confocal Z-series images of DsRed expression in living Tg(ins:DsRed) embryos at 16 dpf. (B) wt; (B’) homozygous mutant. (C) Graphic presentation of the integrated density of fluorescence in the red channel in tcf7l2 exI/exI mutant and wild-type sib controls in Tg(ins:dsRed) at 16 dpf. (D) Quantification of the number of β cells during juvenile growth of tcf7l2 exI/exI and control siblings. (E–E’) Analysis of exocrine pancreas in tcf7l2 exI/exI mutant in Tg(ptf1a:dsRed), (E) wt and (E’) mutant at 16 dpf. (F) Graphic presentation of the integrated density of fluorescence in the red channel in tcf7l2 exI/exI mutant and wild-type sib controls in Tg(ela3l:Crimson) at 7 and 14 dpf. Data were obtained from 6 individuals per genotype, repeated in 2 different experiments. All reference to phenotypes was confirmed by genotyping. The integrated density was obtained using the Fiji software. Values represent the mean ± SEM. Asterisk above column indicate statistical differences among groups *p < 0.05.