Fig. 10

Fig. 10 shh regulates zebrafish liver and pancreas development. (A–C) Endodermal hhex expression at 26 hpf, dorsal view. (A) Wild-type liver (arrow) and pancreas (arrowhead) progenitors express hhex. (B) syu mutants lack hhex expression within the developing endocrine pancreas but retain expression within the liver progenitors (arrow). (C, F) Forced expression of shh RNA enlarges the endocrine pancreas (arrowhead) and dramatically reduces the number of liver progenitors (arrow) that express hhex (91% of injected embryos at 26 hpf, n = 47, and 33% of injected embryos at 34 hpf, n = 147). (D, E) hhex expression at 34 hpf, dorsal view. (D) hhex expression within the liver (arrow) and endocrine pancreas (islet, arrowhead) of a wild-type 34-hpf embryo. (E) syu mutants lack hhex expression within the endocrine pancreas and have an enlarged liver (arrow; syu liver enlarged in 65% of 55 random pairs). (G) Embryos treated with cyclopamine at 12 hpf have normal pancreatic hhex expression at 34 hpf (arrowhead), but lack liver progenitors. (H, I) Liver gata-6 expression, 50 hpf (dorsolateral view). The liver of syu mutants (I) is enlarged relative to wild-types (H) (n = 59% of 34 random pairs). (J, K) Liver enlargement in a 74-hpf syu larva (K) compared with a wild-type sibling (J) (n = 20% of 20 random pairs). Liver size comparisons (D, E and G, H and I, J) were made between randomly paired syu mutants and wild-type siblings. At these stages, the syu liver is either enlarged or equal in size to the wild-type liver in all pairs of embryos.