| [ Summary ] |
All blood cells are derived from hematopoietic stem cells, which possess a self renewal capacity as well as the ability to differentiate into various kinds of blood cells. While primitive hematopoiesis originates from the yolk sack of the embryo, hematopoietic stem cells, capable of supporting adult hematopoiesis, occur in the AGM region. Hematopoietic stem cells can be separated by using cell surface markers, including CD34 antigens. Red blood cells, which are also derived from hematopoietic stem cells, requir erythropoietin for their full maturation. At the final step of red blood cell maturation, the nucleus is extruded by the enzymatic action of DNase II. Iron is essential for the synthesis of hemoglobin in red blood cells, and the IRE/IRP system regulates production of proteins relevant to iron metabolism. |