title: Histochemical Analyses of Biliary Development During Metamorphosis of Xenopus laevis Tadpoles.
abstract: In mammalian liver development, intrahepatic biliary morphogenesis takes place in periportal, but not in pericentral, regions. Liver progenitor cells transiently form epithelial plate structures and then intrahepatic bile ducts around the portal veins under the influence of the mesenchyme. The present study was undertaken to histochemically examine normal biliary development and its dependence on the action of the thyroid hormone triiodothyronine (T3) in Xenopus laevis tadpoles. In these tadpoles, the development of hepatic ducts and intrahepatic biliary ducts commenced along the portal veins at NF stages 48-50 and stages 50-52, respectively, when the blood concentration of thyroid hormone may be still low. Some periportal hepatocytes expressed carbamoylphosphate synthase I and SOX9, which are hepatocyte and biliary cell markers, respectively, suggesting that periportal hepatocytes give rise to biliary epithelial cells. Periportal biliary cells did not form ductal plates, nor was the periportal mesenchyme well developed as seen in fetal mouse livers. jag1 mRNA was moderately expressed in cells of portal veins and biliary epithelial cells, and notch1 and notch2 mRNAs were weakly detectable in biliary epithelial cells during metamorphosis as seen in developing mammalian livers. These results suggest that Notch signaling plays a decisive role in biliary cell differentiation and morphogenesis of Xenopus tadpoles. Anti-thyroid agent treatment of the tadpoles resulted in delayed biliary morphogenesis, suggesting that biliary development may depend on T3. However, T3 treatment of the tadpoles did not enhance biliary development. Thus, T3 may act positively on biliary development at a very low concentration.
authors: Department of Biology, Faculty of Science, Shizuoka University, Oya 836, Suruga-ku, Shizuoka City, Shizuoka 422-8529, Japan.
authors: Tomoya
authors: T
authors: Ueno
authors: Akinori
authors: A
authors: Ishihara
authors: Shinomi
authors: S
authors: Yagi
authors: Toru
authors: T
authors: Koike
authors: Kiyoshi
authors: K
authors: Yamauchi
authors: Nobuyoshi
authors: N
authors: Shiojiri
mesh_terms: D000818:Animals; D001659:Biliary Tract / Q000254:growth & development*; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D050437:Genes, Developmental; D022781:Hepatocytes; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D000072100:Jagged-1 Protein; D007814:Larva / Q000254:growth & development; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008675:Metamorphosis, Biological / Q000502:physiology; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism; D000072099:Serrate-Jagged Proteins; D029867:Xenopus Proteins; D014982:Xenopus laevis / Q000254:growth & development*
chemical_list: D002135:Calcium-Binding Proteins; D036341:Intercellular Signaling Peptides and Proteins; C000606274:Jag1 protein, mouse; D000072100:Jagged-1 Protein; D008565:Membrane Proteins; D051880:Receptors, Notch; D000072099:Serrate-Jagged Proteins; D029867:Xenopus Proteins; C000606280:jag1 protein, Xenopus
keywords: 6-Propylthiouracil; Biliary epithelial cells; Jag1; Liver; Notch signaling