Fig. 7. In situ hybridization analysis of Hnf6 and Hnf1b mRNAs in fetal and neonatal livers. In the wild-type liver, hepatoblasts weakly or moderately express Hnf6 and Hnf1b mRNAs at 12.5 days (A,D), but strong signals of both mRNAs are confined to periportal biliary structures in later development (arrowheads; B,C,E,G). Epithelial cells of the extrahepatic bile duct are strongly positive for both mRNAs (A,D,F). In the knockout liver, Hnf6 and Hnf1b mRNAs are upregulated in hepatoblasts at 12.5 days (arrows; H,M), and in pseudoglandular structures at 15.5 days (star; I,N). Cells of pseudoglandular structures under the hepatic capsule (arrowheads; J,O) and extrahepatic bile duct cells (K,P) strongly express both mRNAs. Also in the neonatal the knockout liver, Hnf6 and Hnf1b mRNAs are upregulated in hepatocytes (L,Q,R) compared with those in the wild-type liver. (R) The nonperiportal region. Periportal epithelial cells and hepatocytes are strongly positive (arrowheads; L,Q). ED, extrahepatic bile duct; PV, portal vein; SI, small intestine. Scale bars: 50 µm. (S) Positive signal profile of Hnf6 mRNA localization from the portal vein to the parenchyma in 15.5-day wild-type (red tracing) and knockout (blue tracing) livers. The level of Hnf6 mRNA expression is upregulated in the parenchymal region of the knockout liver. The use of `weak', `moderate' or `strong' expression of Hnf6 mRNA in the text is based on the profile analyses of positive signals.