Hurle J M, Corson G, Daniels K, Reiter R S, Sakai L Y, Solursh M
Department of Biological Sciences, University of Iowa, Iowa City 52242.
J Cell Sci. 1994 Sep;107 ( Pt 9):2623-34. doi: 10.1242/jcs.107.9.2623.
In this work we have analyzed the presence of elastic components in the extracellular matrices of the developing chick leg bud. The distributions of elastin and fibrillin were studied immunohistochemically in whole-mount preparations using confocal laser microscopy. The association of these constituents of the elastic matrix with other components of the extracellular matrix was also studied, using several additional antibodies. Our results reveal the transient presence of an elastin-rich scaffold of extracellular matrix fibrillar material in association with the establishment of the cartilaginous skeleton of the leg bud. The scaffold consisted of elastin-positive fibers extending from the ectodermal surface of the limb to the central cartilage-forming regions and between adjacent cartilages. Fibrillin immunolabeling was negative in this fibrillar scaffold while other components of the extracellular matrix including: tenascin, laminin and collagens type I, type III and type VI; appeared codistributed with elastin in some regions of the scaffold. Progressive changes in the spatial pattern of distribution of the elastin-positive scaffold were detected in explant cultures in which one expects a modification in the mechanical stresses of the tissues related to growth. A scaffold of elastin comparable to that found in vivo was also observed in high-density micromass cultures of isolated limb mesodermal cells. In this case the elastic fibers are observed filling the spaces located between the cartilaginous nodules. The fibers become reoriented and attach to the ectodermal basal surface when an ectodermal fragment is located at the top of the growing micromass. Our results suggest that the formation of the cartilaginous skeleton of the limb involves the segregation of the undifferentiated limb mesenchyme into chondrogenic and elastogenic cell lineages. Further, a role for the elastic fiber scaffold in coordinating the size and the spatial location of the cartilaginous skeletal elements within the limb bud is also suggested from our observations.
在这项研究中，我们分析了发育中的鸡胚腿芽细胞外基质中弹性成分的存在情况。使用共聚焦激光显微镜，通过免疫组织化学方法研究了弹性蛋白和原纤维蛋白在整装标本中的分布。还使用了几种额外的抗体，研究了弹性基质的这些成分与细胞外基质其他成分之间的关联。我们的结果显示，在腿芽软骨骨架形成过程中，存在富含弹性蛋白的细胞外基质纤维状物质的瞬时支架。该支架由弹性蛋白阳性纤维组成，这些纤维从肢体的外胚层表面延伸至中央软骨形成区域以及相邻软骨之间。在这个纤维状支架中原纤维蛋白免疫标记呈阴性，而细胞外基质的其他成分，包括腱生蛋白、层粘连蛋白以及I型、III型和VI型胶原蛋白，在支架的某些区域与弹性蛋白共分布。在预期组织机械应力会因生长而发生改变的外植体培养中，检测到了弹性蛋白阳性支架空间分布模式的渐进变化。在分离的肢体中胚层细胞的高密度微团培养中，也观察到了与体内相似的弹性蛋白支架。在这种情况下，弹性纤维填充在软骨结节之间的间隙中。当一个外胚层片段位于生长的微团顶部时，纤维会重新定向并附着在外胚层基底面。我们的结果表明，肢体软骨骨架的形成涉及未分化的肢体间充质分离为软骨生成和弹性生成细胞谱系。此外，从我们的观察结果还可以推测，弹性纤维支架在协调腿芽内软骨骨骼元素的大小和空间位置方面发挥了作用。
