Physiology of red and white blood cells

Abstract

The formed elements of blood – red blood cells (erythrocytes), white blood cells (leucocytes) and platelets (thrombocytes) – have a common origin in pluripotent stem cells found in red bone marrow. In the adult, red marrow is limited to the bones of the skull, trunk and proximal end of the long bones. Before birth, in the fetus, red marrow is found in all bones and haemopoietic activity occurs in the liver and spleen up to about 7 months' gestation. The pluripotent stem cells differentiate into colony forming units (CFU) of progenitor (committed stem) cells that give rise to the different cell lineages (Figure 1).