[Do several waves of stem cells follow themselves during hematopoietic development?].

Chimeras built between a quail embryo and a chick yolk sac have led to the demonstration that, in the avian model, intra-embryonic hemopoietic stem cells (HSC) relay HSC originating from the yolk sac. Converging experimental approaches have localized the emergence of intraembryonic HSC to the region of the aorta. Today's session will be dedicated to reviewing experimental data in mouse and man that clearly indicate that this model of hemopoietic ontogeny is also operating in mammals.