Development of the dorsal aorta is a key step in the establishment of the adult blood-forming system, since hematopoietic stem and progenitor cells (HSPCs) arise from ventral aortic endothelium in all vertebrate animals studied. Work in zebrafish has demonstrated that arterial and venous endothelial precursors arise from distinct subsets of lateral plate mesoderm. Earlier studies in the chick showed that paraxial mesoderm generates another subset of endothelial cells that incorporate into the dorsal aorta to replace HSPCs as they exit the aorta and enter circulation. Here we show that a similar process occurs in the zebrafish, where a population of endothelial precursors delaminates from the somitic dermomyotome to incorporate exclusively into the developing dorsal aorta. Whereas somite-derived endothelial cells (SDECs) lack hematopoietic potential, they act as local niche to support the emergence of HSPCs from neighboring hemogenic endothelium. Thus, at least three subsets of endothelial cells (ECs) contribute to the developing dorsal aorta: vascular ECs, hemogenic ECs, and SDECs. Taken together, our findings indicate that the distinct spatial origins of endothelial precursors dictate different cellular potentials within the developing dorsal aorta.

中文翻译：

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源自皮肤染色体组的内皮细胞迁移至背主动脉以支持造血干细胞的出现

背主动脉的发育是成年造血系统建立的关键步骤，因为造血干细胞和祖细胞（HSPC）来自所有研究的脊椎动物的腹主动脉内皮。斑马鱼的研究表明，动脉和静脉内皮前体起源于侧板中胚层的不同子集。雏鸡的早期研究表明，中轴旁中胚层会生成另一层内皮细胞​​，这些细胞整合到背主动脉中，从而在HSPC离开主动脉并进入循环时替代HSPC。在这里，我们显示了类似的过程发生在斑马鱼中，那里的内皮前体群体从体质性皮肤切开术脱层，仅合并到发育中的背主动脉中。体细胞来源的内皮细胞（SDECs）缺乏造血潜能，而它们却是局部利基，支持HSPC从邻近的造血内皮细胞中出现。因此，内皮细胞（EC）的至少三个子集对发育中的背主动脉有贡献：血管EC，造血EC和SDEC。综上所述，我们的发现表明内皮前体的不同空间起源决定了发育中的背主动脉内的不同细胞潜能。