erythr-o-poie--sis - erythrocyte formation
(eh-RITH-roh-poy-EE-sis) The formation of red blood cells in blood-forming tissue. In the early development of a fetus, erythropoiesis takes place in the yolk sac, spleen, and liver. After birth, all erythropoiesis occurs in the bone marrow.
(from Greek ἐρυθρός, erythros, meaning red, and ποίησις, poiēsis, meaning creation, production, making) is the process which produces [red blood cells] (erythrocytes), which is the development from erythropoietic stem cell to mature red blood cell.