Region specific morphogenesis of the axial skeleton in avian embryos: tissue interactions and molecular mechanism

脊椎动物被认为是通过重复和修改节段单元构建的。从根本上说，它的发育单位是体节。体节不仅控制骨骼和肌肉的发育，而且支配脊神经和交感干的发育。为了研究脊椎动物的身体结构是如何形成的，我们研究了体节发育成中轴骨骼的机制。特别是，我们的兴趣集中在肋骨的发展，发展区域特定的鸟类胚胎。肋骨的三个发育隔室：体节与其周围组织之间的相互作用的检查表明，与脊椎关节连接的肋骨的小近端部分（近端肋骨）依赖于脊索和神经管底板发育，而除了近端肋骨之外的长隔室（远端肋骨）依赖于表面外胚层发育。此外，远端肋可以被分成两部分， ...更多信息 ts.体节细胞迁移到体胸膜形成肋内关节远端的肋的一部分（胸骨远端肋），而不进入体胸膜的体节细胞形成该关节近端的一部分（椎骨远端肋）。这些属于远轴和primaxial室，分别，这是最近提出的安伯克。远侧肋形态发生和体节分化：当我们在体节和表面外胚层之间插入薄膜以阻断它们之间的相互作用时，表达Sim 1的皮肌节的侧部和表达Scleroaxis的皮肌节周围的硬化细胞缺失。建议这些区域支持远侧肋骨的发育。躯干体壁肌肉的区域特异性形态发生：腹肌的节段单位。(1)命运映射：结果表明，大部分腹部肌肉来源于第27体节，第26体节和第28体节分别形成吻端和尾端区域。其他腰体节形成肋骨或躯干体壁肌肉。(2)神经支配：在成年母鸡和刚出生的鸡中，我们发现腹部肌肉主要由胸神经支配。由于腹部肌肉的体细胞起源和支配它们的脊神经沿沿着吻尾轴来自不同的水平，因此支配并不总是能让我们知道肌肉的发育起源.肢体发育和肋骨发育：当我们在鸡胚的侧腹区域诱导肢体时，胸骨远端肋骨缺失。肢和胸肋都属于远轴区室，胚胎可能只允许发育其中之一.中轴骨骼原基的确定：我们将鹌鹑表皮或原条异位移植到鸡胚中，并检测了Hox基因的表达和所得骨骼的形态，表明体细胞中胚层产生的上胚层部分在原肠胚形成之前被确定为某种类型的椎骨和/或肋骨。少

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 … More 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