ABSTRACT
The avian model has proved one of the most appropriate to study the cell origins, migrations and interactions which are required for embryonic development of the vascular system. The chicken embryo is accessible, relatively large and develops in a plane. These features allow refined surgery in ovo, in particular replacement of cells, tissues or rudiments by corresponding structures from quail embryos. Such heterospecific combinations are the means of a labelling system (Le Douarin, 1973), with which developmental migration pathways, sites of arrest and differentiation cues have been established for various cell types. The species of origin and/or the cell type are identified with monoclonal antibodies (moabs), in addition to the contrasting structures of heterochromatin in the cell nuclei of the quail and chicken species, on which diagnosis originally relied. In the case of the vascular system, moab MB1/QH1 (Péault et al., 1983; Pardanaud et al., 1987), specific for quail endothelial cells (EC) and hemopoietic cells (HC), easily detects single quail cells in a chick host, in particular EC precursors before they integrate into functional vascular tubes.
