Fig. 2

Absence of Dorsal Pancreatic Bud Derived β Cells in smo Mutants

(A and B) Ventral confocal images of Tg(sox17:DsRed)^s903 (red) and β-catenin (green) expression, comparing wild-type (A) and smo mutants (B) at 18 hpf (mid-trunk region). Tg(sox17:DsRed)^s903-expressing endodermal cells show a similar arrangement and distribution around the midline (asterisks) in wild-type (A) and smo mutants (B).

(C–F) Dorsal views of Tg(ins:GFP) embryos stained for GFP (green), comparing wild-type (C and E) and smo mutants (D and F) at 18 (C and D) and 24 (E and F) hpf. (C and D) Tg(ins:GFP)-expressing cells are completely missing in 18 hpf smo mutants. Cells in the anterior neural tube (arrowhead) also express the ins:GFP transgene. (E) Tg(ins:GFP)-expressing cells form a cluster in 24 hpf wild-type embryos (arrow). (F) Tg(ins:GFP)-expressing cells are completely missing in most smo mutants, though in approximately 5% of the mutants (n > 100 mutants examined), one or two Tg(ins:GFP)-expressing cells can be observed ([F], arrow).

(G–J) Confocal projections of wild-type (G and I) and smo mutant (H and J) endoderm at 34 (G and H) and 96 (I and J) hpf. (G and H) Tg(gutGFP) ^s854 embryos were stained for Islet1 (red) and Insulin (blue). (G) The endodermal cells (green) form a solid multicellular rod, and pancreatic endocrine cells (arrow and inset) aggregate into one cluster in wild-type embryos. (H) In smo mutants, the endodermal cells fail to condense into a midline rod, and pancreatic endocrine cells are completely absent. (I and J) Tg(ins:GFP) embryos were stained for pan-Cadherin (red) and 2F11 (blue) to mark the endoderm and ductal structures, respectively. (I) Tg(ins:GFP)-expressing β cells (arrow) form a cluster inside the wild-type pancreas. (J) Although the morphology of the pancreas and liver is disrupted, Tg(ins:GFP)-expressing β cells (arrows) appear in smo mutants in ventral pancreatic bud derived tissues. L, liver; P, pancreas; IB, intestinal bulb.