[Embryology of vessels].
Endothelial emergence is the best known aspect of vessel formation during embryogenesis. It has been analyzed in an avian model of chimeras at the time of organogenesis or morphogenesis. These chimeras involve two species, chick and quail, whose cells may be distinguished on the basis of distinct nuclear heterochromatin patterns or through the use of antibodies that are species and lineage specific. QH1, a monoclonal antibody obtained in our group, whose affinity is restricted to the quail hemangioblastic lineage (endothelial and hemopoietic cells), has been a sensitive probe to study the origin of these cells in various chimeric patterns. By transplanting organ rudiments or primordial germ layers, we have shown that endothelium emergence in organ rudiments occurs through two different mechanisms, vasculogenesis or in situ differentiation, and angiogenesis or colonization by extrinsic precursors. Vasculogenesis occurs in the mesoderm of internal organ rudiments while angiogenesis occurs in external rudiments. The conclusion is that associated endoderm exerts a positive influence on the emergence of endothelial progenitors from mesodermal precursors.
Dieterlen-Lièvre
F
F
Institut d'Embryologie Cellulaire et Moléculaire du CNRS, Collège de France, Nogent-sur-Marne.
Pardanaud
L
L
D000818:Animals; D001808:Blood Vessels / Q000196:embryology*; D002454:Cell Differentiation; D002642:Chick Embryo; D004730:Endothelium, Vascular / Q000196:embryology; D006410:Hematopoiesis; D006801:Humans
L'embryologie des vaisseaux.