Department of Cell and Developmental Biology, University College London, UK.
Centre for Regenerative Medicine, The University of Edinburgh, UK.
Dev Biol. 2022 Oct;490:13-21. doi: 10.1016/j.ydbio.2022.06.015. Epub 2022 Jun 30.
The head-tail axis in birds and mammals develops from a growth zone in the tail-end, which contains the node. This growth zone then forms the tailbud. Labelling experiments have shown that while many cells leave the node and tailbud to contribute to axial (notochord, floorplate) and paraxial (somite) structures, some cells remain resident in the node and tailbud. Could these cells be resident axial stem cells? If so, do the node and tailbud represent an instructive stem cell niche that specifies and maintains these stem cells? Serial transplantation and single cell labelling studies support the existence of self-renewing stem cells and heterotopic transplantations suggest that the node can instruct such self-renewing behaviour. However, only single cell manipulations can reveal whether self-renewing behaviour occurs at the level of a cell population (asymmetric or symmetric cell divisions) or at the level of single cells (asymmetric divisions only). We combine data on resident cells in the node and tailbud and review it in the context of axial development in chick and mouse, summarising our current understanding of axial stem cells and their niche and highlighting future directions of interest.
鸟类和哺乳动物的头尾轴由尾部的生长区发育而来，该生长区包含节点。这个生长区随后形成尾芽。标记实验表明，虽然许多细胞离开节点和尾芽，以参与轴向（脊索、基板）和轴旁（体节）结构的形成，但有些细胞仍然留在节点和尾芽中。这些细胞会不会是常驻的轴向干细胞？如果是这样，那么节点和尾芽是否代表了一个指定和维持这些干细胞的有指导作用的干细胞生态位？连续移植和单细胞标记研究支持自我更新干细胞的存在，而异位移植表明节点可以指导这种自我更新行为。然而，只有单细胞操作才能揭示自我更新行为是在细胞群体水平上（不对称或对称细胞分裂）还是在单个细胞水平上（仅不对称分裂）发生。我们结合了节点和尾芽中常驻细胞的数据，并在鸡和鼠的轴向发育背景下对其进行了综述，总结了我们目前对轴向干细胞及其生态位的理解，并强调了未来感兴趣的方向。
