Department of Biological Sciences and Centre for BioImaging Sciences (CBIS), National University of Singapore, Singapore 117543, Singapore.
Dev Biol. 2013 Sep 1;381(1):134-43. doi: 10.1016/j.ydbio.2013.05.030. Epub 2013 Jun 13.
In teleosts, such as medaka, ossification of the vertebral column starts with the mineralization of the notochordal sheath in a segmental pattern. This establishes the chordal centrum, which serves as the basis for further ossifications by sclerotome derived osteoblasts generating the vertebral body. So far, it is unclear which cells produce the notochordal sheath and how a segmental pattern of mineralization is established in teleosts. Here, we use a transgenic medaka line that expresses nlGFP under the control of the col10a1 promoter for in vivo analysis of vertebral body formation. We show that col10a1:nlGFP expression recapitulates endogenous col10a1 expression. In the axial skeleton, col10a1:nlGFP cells appear prior to the mineralization of the notochordal sheath in a segmental pattern. These cells remain on the outer surface of the chordal centra during mineralization as well as subsequent perichordal ossification of the vertebral bodies. Using twist1a1:dsRed and osx:mCherry transgenic lines we show that a subset of col10a1:nlGFP cells is derived from sclerotomal precursors and differentiates into future osteoblasts. For the first time, this shows a segmental occurrence of putative osteoblast precursors in the vertebral centra prior to ossification of the notochordal sheath. This opens the possibility that sclerotome derived cells in teleosts are implicated in the establishment of the mineralized vertebral column in a similar manner as previously described for tetrapods.
在硬骨鱼类中，如斑马鱼，脊柱的骨化是从脊索鞘的分段矿化开始的。这就形成了脊索中心体，它为软骨内成骨细胞产生的椎体的进一步骨化提供了基础。到目前为止，还不清楚是哪些细胞产生了脊索鞘，以及在硬骨鱼类中是如何建立分段矿化模式的。在这里，我们使用了一种转基斑马鱼系，该系在 col10a1 启动子的控制下表达 nlGFP，用于椎体形成的体内分析。我们表明，col10a1:nlGFP 的表达重现了内源性 col10a1 的表达。在轴性骨骼中，col10a1:nlGFP 细胞在脊索鞘的分段矿化之前出现。这些细胞在矿化过程中以及随后的椎体周围骨化过程中，仍然位于脊索中心体的外表面。使用 twist1a1:dsRed 和 osx:mCherry 转基因系，我们表明，col10a1:nlGFP 细胞的一个亚群来源于软骨内成骨细胞前体，并分化为未来的成骨细胞。这首次表明，在脊索鞘矿化之前，椎骨中心体中存在潜在的成骨细胞前体的分段发生。这为硬骨鱼类中软骨内成骨细胞衍生的细胞在矿化的脊柱建立中发挥作用提供了可能性，其方式与以前描述的四足动物类似。
