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Abstract
The endoderm is the innermost germ layer that forms the linings of the respiratory and gastrointestinal tracts, and their associated organs, during embryonic development. Xenopus embryology experiments have provided fundamental insights into how the endoderm develops in vertebrates, including the critical role of TGFβ-signaling in endoderm induction,elucidating the gene regulatory networks controlling germ layer development and the key molecular mechanisms regulating endoderm patterning and morphogenesis. With new genetic, genomic, and imaging approaches, Xenopus is now routinely used to model human disease, discover mechanisms underlying endoderm organogenesis, and inform differentiation protocols for pluripotent stem cell differentiation and regenerative medicine applications. In this chapter, we review historical and current discoveries of endoderm development in Xenopus, then provide examples of modeling human disease and congenital defects of endoderm-derived organs using Xenopus.
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Affiliation(s)
- Nicole A Edwards
- Division of Developmental Biology, Center for Stem Cell and Organoid Medicine, Perinatal Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.
| | - Aaron M Zorn
- Division of Developmental Biology, Center for Stem Cell and Organoid Medicine, Perinatal Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States.
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Shiojiri N, Tanaka S, Kawakami H. The hepatic architecture of the coelacanth differs from that of the lungfish in portal triad formation. Okajimas Folia Anat Jpn 2019; 96:1-11. [PMID: 31462619 DOI: 10.2535/ofaj.96.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The liver architecture of vertebrates can be classified into two types, the portal triad type (having periportal bile ducts) and the non-portal triad type (having non-periportal bile ducts). The former is detectable in the tetrapod liver whereas the lungfish liver has the latter. It remains to be revealed which type of hepatic architecture the coelacanth, which together with the lungfish belongs to the Sarcopterygii, possesses. The present study was undertaken to determine the histological characteristics of the coelacanth liver, and to compare with those of other vertebrates. The coelacanth liver had periportal bile ducts and ductules as detected in mammalian livers. The hepatic artery was found around large portal veins. Hagfish, shark, bichir, sturgeon, bowfin and frog livers had periportal bile ducts and bile ductules, whereas most intrahepatic bile ducts of the lungfish were independent of the distribution of the portal veins as seen in the Otocephala and Euteleostei. The lungfish liver developed duct and ductule structures in the parenchyma. These data indicate that the coelacanth liver had a mammalian-type hepatic architecture with a portal triad, and that the ancestors of tetrapods may have had a portal triad-type liver architecture.
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Affiliation(s)
| | - Sho Tanaka
- Department of Marine Biology, School of Marine Science and Technology, Tokai University
| | - Hayato Kawakami
- Laboratory for Electron Microscopy, Kyorin University School of Medicine.,Department of Anatomy, Kyorin University School of Medicine
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Shiojiri N, Kametani H, Ota N, Akai Y, Fukuchi T, Abo T, Tanaka S, Sekiguchi J, Matsubara S, Kawakami H. Phylogenetic analyses of the hepatic architecture in vertebrates. J Anat 2017; 232:200-213. [PMID: 29205342 DOI: 10.1111/joa.12749] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/24/2017] [Indexed: 12/18/2022] Open
Abstract
The mammalian liver has a structural and functional unit called the liver lobule, in the periphery of which the portal triad consisting of the portal vein, bile duct and hepatic artery is developed. This type of hepatic architecture is detectable in many other vertebrates, including amphibians and birds, whereas intrahepatic bile ducts run independently of portal vein distribution in actinopterygians such as the salmon and tilapia. It remains to be clarified how the hepatic architectures are phylogenetically developed among vertebrates. The present study morphologically and immunohistochemically analyzed the hepatic structures of various vertebrates, including as many classes and subclasses as possible, with reference to intrahepatic bile duct distribution. The livers of vertebrates belonging to the Agnatha, Chondrichthyes, Amphibia, Aves, Mammalia, and Actinopterygii before Elopomorpha, had the portal triad-type architecture. The Anguilliformes livers developed both periportal bile ducts and non-periportal bile ducts. The Otocephala and Euteleostei livers had independent configuration of bile ducts and portal veins. Pancreatic tissues penetrated the liver parenchyma along portal veins in the Euteleostei. The liver of the lungfish, which shares the same origin with amphibians, did not have the portal triad-type architecture. Teleostei and lungfish livers had ductular development in the liver parenchyma similar to oval cell proliferation in injured mammalian livers. Euteleostei livers had penetration of significant numbers of independent portal veins from their intestines, suggesting that each liver lobe might receive a different blood supply. The hepatic architectures of the portal triad-type changed to non-portal triad-type architecture along the evolution of the Actinopterygii. The hepatic architecture of the lungfish resembles that of the Actinopterygii after Elopomorpha in intrahepatic biliary configuration, which may be an example of convergent evolution.
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Affiliation(s)
- Nobuyoshi Shiojiri
- Department of Biology, Faculty of Science, Shizuoka University, Shizuoka, Japan
| | - Harunobu Kametani
- Department of Biology, Faculty of Science, Shizuoka University, Shizuoka, Japan
| | - Noriaki Ota
- Department of Biology, Faculty of Science, Shizuoka University, Shizuoka, Japan
| | - Yusuke Akai
- Department of Biology, Faculty of Science, Shizuoka University, Shizuoka, Japan
| | - Tomokazu Fukuchi
- Department of Biology, Faculty of Science, Shizuoka University, Shizuoka, Japan
| | - Tomoka Abo
- Department of Biology, Faculty of Science, Shizuoka University, Shizuoka, Japan
| | - Sho Tanaka
- Department of Marine Biology, School of Marine Science and Technology, Tokai University, Shizuoka, Japan
| | - Junri Sekiguchi
- Laboratory for Electron Microscopy, Kyorin University School of Medicine, Mitaka, Japan.,Department of Anatomy, Kyorin University School of Medicine, Mitaka, Japan
| | - Sachie Matsubara
- Laboratory for Electron Microscopy, Kyorin University School of Medicine, Mitaka, Japan.,Department of Anatomy, Kyorin University School of Medicine, Mitaka, Japan
| | - Hayato Kawakami
- Laboratory for Electron Microscopy, Kyorin University School of Medicine, Mitaka, Japan.,Department of Anatomy, Kyorin University School of Medicine, Mitaka, Japan
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