Aoyama Hirohiko, Mizutani-koseki Supyoko, Koseki Haruhiko
Department of Anatomy and Developmental Biology, Graduate School of Medical Sciences, Hiroshima University, Minami-ku, Hiroshima, Japan.
Int J Dev Biol. 2005;49(2-3):325-33. doi: 10.1387/ijdb.041932ha.
When the thoracic somitic mesoderm was separated from the neural tube and the notochord with a piece of aluminum foil in two-day chick embryos, seven days after the operation ribs lacked their proximal part. The embryos were rescued by co-transplanting the notochord, the ventral half of neural tube, or QT6 cells transformed with Shh, on the somite side of the aluminum foil insert. Thus, proximal rib development depends on the notochord and the ventral neural tube, an effect which might be mediated through Shh secreted by these axial tissues. On the other hand, when the thoracic somitic mesoderm was separated from the surface ectoderm by a piece of polyethylene terephthalate film, the distal parts of the ribs were missing, suggesting that distal rib development depends on surface ectoderm. In these embryos, expression of Pax3 was weak and perturbed showing that the dermomyotome developed abnormally. It is not clear whether the development of distal rib is mediated by the dermomyotome, or the ectoderm. It has previously been shown that sternal rib development depends on lateral plate mesoderm. As to the distal rib, it is considered to be composed of two parts. Thus, the rib is composed of three developmental compartments, in agreement with a recently presented classification of somite derivatives as primaxial and abaxial.
在两天龄的鸡胚中，用一片铝箔将胸段体节中胚层与神经管和脊索分离后，手术七天后肋骨缺少其近端部分。通过在铝箔插入物的体节一侧共移植脊索、神经管腹侧半部分或用Shh转化的QT6细胞，胚胎得以挽救。因此，近端肋骨发育依赖于脊索和腹侧神经管，这种作用可能是由这些轴向组织分泌的Shh介导的。另一方面，当用一片聚对苯二甲酸乙二酯薄膜将胸段体节中胚层与表面外胚层分离时，肋骨的远端部分缺失，这表明远端肋骨发育依赖于表面外胚层。在这些胚胎中，Pax3的表达较弱且受到干扰，表明皮肌节发育异常。目前尚不清楚远端肋骨的发育是由皮肌节还是外胚层介导的。先前已表明胸骨肋骨发育依赖于侧板中胚层。至于远端肋骨，它被认为由两部分组成。因此，肋骨由三个发育区室组成，这与最近提出的将体节衍生物分为原轴和副轴的分类一致。
