Endoderm is required for vascular endothelial tube formation, but not for angioblast specification

Steven A. Vokes, Paul A. Krieg

Research output: Contribution to journalArticlepeer-review

83 Scopus citations


Angioblasts, the precursor cells that comprise the endothelial layer of blood vessels, arise from a purely mesodermal population. Individual angioblasts coalesce to form the primary vascular plexus through a process called vasculogenesis. A number of reports in the literature suggest that signals from the adjacent endoderm are necessary to induce angioblast specification within the mesoderm. We present evidence, using both embryological and molecular techniques, indicating that endoderm is not necessary for the induction of angioblasts. Xenopus embryos that had endoderm physically removed at the onset of gastrulation still express vascular markers. Furthermore, animal caps stimulated with bFGF form angioblasts in the absence of any detectable endodermal markers. These results show that endoderm is not required for the initial formation of angioblasts. While Xenopus embryos lacking endoderm contain aggregates of angioblasts, these angioblasts fail to assemble into endothelial tubes. Endothelial tube formation can be rescued, however, by implantation of endodermal tissue from sibling embryos. Based on these studies in Xenopus, and corroborating experiments using the quail embryo, we conclude that endoderm is not required for angioblast specification, but does play an essential role in the formation of vascular tubes.

Original languageEnglish (US)
Pages (from-to)775-785
Number of pages11
Issue number3
StatePublished - 2002


  • Endoderm
  • Induction
  • Tubulogenesis
  • Vasculogenesis
  • Xenopus laevis

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology


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