2005 Fiscal Year Final Research Report Summary
Region specific morphogenesis of the axial skeleton in avian embryos: tissue interactions and molecular mechanism
| Project/Area Number |
14370006
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General anatomy (including Histology/Embryology)
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| Research Institution | Hiroshima University |
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Principal Investigator |
AOYAMA Hirohiko Hiroshima University, Graduate School of Medical Sciences, Professor, 大学院医歯薬学総合研究科, 教授 (70143948)
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| Co-Investigator(Kenkyū-buntansha) |
SAKAMOTO Nobuyuki Hiroshima University, Graduate School of Medical Sciences, Assistant, 大学院医歯薬学総合研究科, 助手 (90346487)
MATSUI Koji Hiroshima University, Graduate School of Medical Sciences, Assistant, 大学院医歯薬学総合研究科, 助手 (80183945)
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| Project Period (FY) |
2002 – 2005
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| Keywords | bodyplan / morphogenesis / vertebrate / avian embryo / somitic mesoderm / axial skeleton / body wall muscles / phylogenesis |
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| Research Abstract |
Vertebrates are considered to be constructed by repeating and modifying segmental unit. Fundamentally, its developmental unit is somite. Not only the skeleton and muscles derived from somites, but also development of the spinal nerve and sympathetic trunk is under control of somites. To consider how the body plan is established in the vertebrate, we have investigated the mechanism of development from somites into the axial skeleton. Especially, our interest is focused on the development of the rib that develops region-specifically in the avian embryo.
1. Three developmental compartment of the rib : Examination of interaction between the somites and their surrounding tissues showed that small proximal part of the rib articulating with the vertebra (proximal rib) develops depending on the notochord and the floor plate of neural tube, and long compartment other than the proximal rib (distal rib) develops depending on the surface ectoderm. Further, the distal rib can be divided into tow par
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ts. Somite cells migrate into the somatopleura form a part of the rib distal to the intra-rib articulation (sternal distal rib), while somite cells which do not enter the somatopleura form a part proximal to this joint (vertebral distal rib). These belong to the abaxial and primaxial compartment, respectively, which are recently proposed by Ann Burke.
2. Distal rib morphogenesis and somite differentiation : When we inserted thin film between the somite and the surface ectoderm to block the interaction between them, lateral part of the dermomyotome expressing Sim1 and sclerotomal cells at the periphery of dermomyotome expressing Scleroaxis were missing. These regions are suggested to support the distal rib development.
3. Region specific morphogenesis of trunk body wall muscles : Segmental unit of abdominal muscles.
(1) Fate mapping: We showed that most part of the abdominal muscles was derived from the 27th somite and the 26th and the 28th somite formed the rostral and the caudal end region, respectively. Other lumbar somites form either the ribs or the trunk body wall muscles.
(2) Innervations: In adult hen and chicken just after birth, we found that the abdominal muscles were largely innervated by the thoracic nerves. Because the somitic origin of abdominal muscles and the spinal nerve innervating them were from different levels along rostro-caudal axis, innervations will not always allow us to know the developmental origin of muscles.
4. Limb development and rib development : When we induced a limb at the flank region in a chick embryo, the sternal distal ribs were missing. Both the limb and the sternal rib belong to the abaxial compartment and the embryo might allow to develop only one of them.
5. Determination of the primordium of the axial skeleton : We transplanted heterotopically the quail epidermis or primitive streak into chick embryo and examined expression of Hox genes and morphology of resultant skeleton, showing that a part of epiblast where the somitic mesoderm arises was determined to become a certain type of vertebrae and/or ribs just before gastrulation. Less
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Research Products
(2 results)
