Mills K R, Kruep D, Saha M S
Department of Biology, College of William and Mary, Williamsburg, Virginia, 23187, USA.
Dev Biol. 1999 May 15;209(2):352-68. doi: 10.1006/dbio.1999.9245.
Required to supply nutrients and oxygen to the growing embryo, the vascular system is the first functional organ system to develop during vertebrate embryogenesis. Although there has been substantial progress in identifying the genetic cascade regulating vascular development, the initial stages of vasculogenesis, namely, the origin of vascular endothelial cells within the early embryo, remain unclear. To address this issue we constructed a fate map for specific vascular structures, including the aortic arches, endocardium, dorsal aorta, cardinal veins, and lateral abdominal veins, as well as for the red blood cells at the 16-cell stage and the 32-cell stage of Xenopus laevis. Using genetic markers to identify these cell types, our results suggest that vascular endothelial cells can arise from virtually every blastomere of the 16-cell-stage and the 32-cell-stage embryo, with different blastomeres preferentially, though not exclusively, giving rise to specific vascular structures. Similarly, but more surprisingly, every blastomere in the 16-cell-stage embryo and all but those in the most animal tier of the 32-cell-stage embryo serve as progenitors for red blood cells. Taken together, our results suggest that during normal development, both dorsal and ventral blastomeres contribute significantly to the vascular endothelial and red blood cell lineages.
血管系统需要为发育中的胚胎提供营养和氧气，它是脊椎动物胚胎发育过程中第一个发育的功能器官系统。尽管在确定调节血管发育的基因级联方面取得了重大进展，但血管生成的初始阶段，即早期胚胎中血管内皮细胞的起源，仍不清楚。为了解决这个问题，我们构建了非洲爪蟾在16细胞期和32细胞期特定血管结构的命运图谱，这些结构包括主动脉弓、心内膜、背主动脉、主静脉和侧腹静脉，以及红细胞的命运图谱。利用遗传标记来识别这些细胞类型，我们的结果表明，血管内皮细胞几乎可以起源于16细胞期和32细胞期胚胎的每个卵裂球，不同的卵裂球优先（但并非唯一）产生特定的血管结构。同样，但更令人惊讶的是，16细胞期胚胎的每个卵裂球以及32细胞期胚胎除最上层动物层的卵裂球外的所有卵裂球都可作为红细胞的祖细胞。综上所述，我们的结果表明，在正常发育过程中，背侧和腹侧卵裂球对血管内皮细胞和红细胞谱系都有显著贡献。
