Development of the apical ectodermal ridge in the chick wing bud.
Development of the apical ectodermal ridge in the chick wing bud.
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发表时间：
1984-04
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通讯作者：
John F. Fallon;W. Todt
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作者：
John F. Fallon;W. Todt
第18期至第23期鸡翅芽尖的组织学检查揭示了以下内容。最初，翅芽由立方形到柱状上皮覆盖，上覆周壁。顶端外胚层的加厚直到第18期晚期（36对体节）才明显，此时翅芽出现。在晚期18，外胚层内层的细胞沿垂直于上皮-间充质界面的轴沿着略微伸长。明确的顶端外胚层嵴形态，即，假复层柱状上皮与上覆的周膜，直到20期才明显。随后，脊沿着翅芽的前后周长延长。我们证明，组织学上的翅芽顶端外胚层脊是不对称的前后轴，在有更多的脊与后中胚层。其他观测包括在脊最厚部分的底部的凹槽的空间和时间位置。凹槽可以与远端翼元件的规格相关联。在第20阶段首次看到凹槽，并在第23阶段变得更加突出。还观察到外胚层细胞死亡的前后进展。这种情况从第18阶段后期开始，并持续到所审查的每个阶段。
Histological examination of the stage-18 to stage-23 chick wing bud apex revealed the following. Initially, the wing bud was covered by a cuboidal to columnar epithelium with an overlying periderm. Thickening of the apical ectoderm was not obvious until late stage 18 (36 pairs of somites), after the appearance of the wing bud. At late stage 18, cells of the inner layer of ectoderm had elongated slightly along an axis perpendicular to the epithelial-mesenchymal interface. Well-defined apical ectodermal ridge morphology, i.e., pseudostratified columnar epithelium with an overlying periderm, was not apparent until stage 20. Subsequently the ridge lengthened along the anteroposterior perimeter of the wing bud. We demonstrated histologically that the apical ectodermal ridge of the wing bud was asymmetric with respect to the anteroposterior axis, in that there was more ridge associated with posterior mesoderm. Other observations include the spatial and temporal location of a groove in the base of the thickest part of the ridge. The groove can be correlated with the specification of distal wing elements. The groove was first seen at stage 20 and became more prominent through stage 23. An anteroposterior progression of ectodermal cell death was also observed. This began at late stage 18 and continued through each of the stages examined.