Intraaortic hemopoietic cells are derived from endothelial cells during ontogeny.
We have investigated the developmental relationship of the hemopoietic and endothelial lineages in the floor of the chicken aorta, a site of hemopoietic progenitor emergence in the embryo proper. We show that, prior to the onset of hemopoiesis, the aortic endothelium uniformly expresses the endothelium-specific membrane receptor VEGF-R2. The onset of hemopoiesis can be determined by detecting the common leukocyte antigen CD45. VEGF-R2 and CD45 are expressed in complementary fashion, namely the hemopoietic cluster-bearing floor of the aorta is CD45(+)/VEGF-R2(-), while the rest of the aortic endothelium is CD45(-)/VEGF-R2(+). To determine if the hemopoietic clusters are derived from endothelial cells, we tagged the E2 endothelial tree from the inside with low-density lipoproteins (LDL) coupled to DiI. 24 hours later, hemopoietic clusters were labelled by LDL. Since no CD45(+) cells were inserted among endothelial cells at the time of vascular labelling, hemopoietic clusters must be concluded to derive from precursors with an endothelial phenotype.
Institut d'Embryologie Cellulaire et Moléculaire du CNRS et du Collège de France; 49 bis, Avenue de la Belle Gabrielle, France. jaffredo@infobiogen.fr
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Jaffredo
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Gautier
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A
Eichmann
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Dieterlen-Lièvre
D000818:Animals; D001011:Aorta / Q000196:embryology* / Q000648:ultrastructure; D019070:Cell Lineage; D002642:Chick Embryo; D003370:Coturnix / Q000196:embryology; D004730:Endothelium, Vascular / Q000196:embryology* / Q000648:ultrastructure; D006410:Hematopoiesis; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D017493:Leukocyte Common Antigens / Q000302:isolation & purification; D008077:Lipoproteins, LDL / Q000302:isolation & purification; D008954:Models, Biological; D020794:Receptor Protein-Tyrosine Kinases / Q000302:isolation & purification; D017978:Receptors, Growth Factor / Q000302:isolation & purification; D040262:Receptors, Vascular Endothelial Growth Factor
D008077:Lipoproteins, LDL; D017978:Receptors, Growth Factor; C032629:acetyl-LDL; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor; D017493:Leukocyte Common Antigens