Noun
the formation of blood cells in the living body (especially in the bone marrow)
Source: WordNetFormation of red blood cells (haematopoiesis) Vitamin A may be needed for normal haematopoiesis ; Oren T, Sher JA, Evans T. "Hematopoiesis and retinoids: development and disease". Source: Internet
In children, haematopoiesis occurs in the marrow of the long bones such as the femur and tibia. Source: Internet
This is the classical way of describing haematopoiesis. Source: Internet