Figure 4.

Lack of expression of several essential regulators of pancreatic development in ngn3 mutant mice. In wild-type pancreas, Pdx1 is initially expressed in endodermal progenitors in the pancreatic bud (a), whereas Pax4 (b), Pax6 (c), and NeuroD (d) are expressed in differentiating endocrine cells, and p48 (e) is expressed in the differentiating exocrine tissue. In ngn3-deficient mice, Pdx1 (a′) remains expressed in pancreatic progenitors, and p48 remains expressed in exocrine cells (e′), whereas expression of Pax4 (b′), Pax6 (c′), and NeuroD (d′) is completely missing, suggesting that ngn3 is essential for the specification or differentiation of endocrine precursors. An asterisk (*) marks the background in the lumen of the pancreatic bud also observed in control experiments. Expression of NeuroD in enteroendocrine cells of the gut (arrowheads in d) is also lost in ngn3 mutant mice (d′). (a–c and a′–c′) Pancreas at E10.5. (d–e and d′–e′) Pancreas at E15.5.