<i>sox9b</i> mutants display defective HPD patterning during organ development.

<p>(A–B) Labeling for the hepatocyte marker <i>Tg(fabp10:</i>ras-GFP) (green) and the HPD marker 2F11 (red) in wild-type and <i>sox9b</i> mutant embryos at 50 hpf. 2F11 labeling in the HPD primordium is noticeably reduced in <i>sox9b</i> mutants. (A′–B′) Same views as (A–B), but only showing the 2F11 immunostaining. (C–D) In wild-type, Prox1 expression marks the liver and pancreas and is largely absent from the HPD primordium (C). In contrast, Prox1 is abnormally expressed in the HPD primordium in <i>sox9b</i> mutants (D). (A′–B′, C–D) Brackets mark the HPD primordium. (E) By 80 hpf, different compartments of the HPD system, including the cystic duct (CD), common bile duct (CBD), gallbladder (GB), extrahepatic duct (EHD) have become evident in wild-type. (F) In <i>sox9b</i> mutants, the HPD system is dysmorphic and its compartments are indistinguishable based on morphology. The gallbladder is also often missing. (E′–F′) Same views as (E–F), but only showing 2F11 immunostaining. (G–H) Whole-mount <i>in situ</i> hybridization showing <i>sox17</i> expression in the gallbladder primordium in wild-type and <i>sox9b</i> mutants at 52 (G) and 72 (H) hpf. <i>sox17</i> expression is greatly reduced or absent in <i>sox9b</i> mutants. The proportion of mutants showing the corresponding phenotype is indicated. Arrows point to the gallbladder primordium. (A–F, A′–F′) All images are projections of confocal z-stacks. Ventral views. (G–H) Dorsal views. Anterior (A) to the top. Pa, pancreas; Li, liver; EPD, extrapancreatic duct. Scale bars, 20 µm.