Synthesis of red blood cells. As erythroid precursors mature, they undergo changes in metabolism, globin synthesis and eventual extrusion of the nucleus. The life span of a RBC is approximately 120 days, so continued renewal is ongoing. Erythropoiesis requires normal supply of vitamins (folate and B12), nutrients and essential minerals (iron). Dyserythropoiesis is abnormal RBC synthesis, characterized by nuclear abnormalities, including abnormal chromatin pattern, bizarre shapes, and nuclear fragmentation. The control of erythropoiesis is multifactorial, and the bone marrow can respond to a need for increase in RBCs by releasing reticulocytes into blood and developing a sustained increase in red cell synthesis.