All blood cells originate from the uncommitted pluripotent stem cells, which give rise to lymphoid stem cells and myeloid stem cells. Myeloid stem cells are the precursors of RBCs, granulocytes, monocytes, and platelets. Hormones such as erythropoietin, thrombopoietin, and granulocyte colony-stimulating factor initiate the differentiation of the various cellular elements. The life span of a circulating RBC is 120 days.
Excerpted from BCSC 2020-2021 series: Section 1 - Update on General Medicine. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.