Molecular aspects of haematopoietic stem cell emergence

Haematopoietic stem cells (HSC) are routinely used today in clinical haematology to treat leukaemia and recent findings offer further possibilities of using them in other fields of medicine. Before of this type of application, however, it is very important to precisely reveal their characteristics and genetic programs. To understand the properties of the adult HSCs it is important to know from where they come from in the embryo. One of the useful models to investigate these processes is the avian embryo. Pioneer experiments on bird embryos demonstrated that haematopoietic stem cells, which ensure the needs of the adult blood system in the bone marrow, are not derived from the yolk sac but have an intraembryonic source. The accessibility of avian embryos to manipulation provide the possibility to study cellular migrations and interactions. In addition, the growing number of chicken genetic databases raises the possibility of revealing the regulatory mechanisms of these processes. The work presented in this book revealed some important new findings concerning the different genetic programs governing early haematopoietic differentiation.