Main principles of hematopoiesis

All mature cells are originated from the pluripotent hematopoietic stem cells (HSCs)
Maturation of cells is going through several intermediate steps.
Capacity to differentiate is increasing and capacity to divide and sel-production is decreasing during maturation. Mature blood cells are not able to divide.
Usually only mature cells can reach blood
Hematopoiesis must and is very carefully regulated to hold stable number of cells in the blood