Hematopoiesis is a complicated process that is controlled by both intrinsic and extrinsic cellular factors. It is a process of progression by which the diverse cell pedigrees that develop the blood and immune system are spawned from a shared pluripotent hematopoietic stem cell (HSC). Throughout the lifespan of an adult, two distinct hematopoietic systems are present, both resulting through embryonic development but only one of them enduring into adulthood.
