Figure 1.
Onset of differentiated gene expression in exocrine pancreas. (A) Pdx1 expression domain indicated by Xgal staining in Pdx1:lacZ/+ transgenic mice. E11.5, isolated foregut from E11.5 mouse embryo demonstrating Pdx1 expression in posterior foregut. a, gastric antrum; dp, dorsal pancreatic bud; vp, ventral pancreatic bud; bb, biliary bud; duo, duodenum. (B) E14.5, Xgal/eosin-stained section demonstrates Pdx1 expression in entire pancreatic epithelium. (C) E16.5, Xgal/anti-amylase–stained section shows down-regulation of Pdx1 expression in developing acinar cells, ongoing expression in immature ductal epithelium (arrows), and budding islet cells. (D) E18.5, Xgal/anti-keratin–stained section shows down-regulation of Pdx1 expression in keratin-positive mature ductal epithelium. Note ongoing expression in budding islets (arrows). Original magnification 40×.