Hematopoietic stem cells (HSCs) are multipotent, self-renewing progenitor cells that develop from mesodermal hemangioblast cells. All differentiated blood cells from the lymphoid and myeloid lineages arise from HSCs. HSCs can be found in adult bone marrow, peripheral blood, and umbilical cord blood. Classic studies in mice describe two populations of Hematopoietic Stem Cells, Long Term and Short Term. Long term HSCs are capable of self renewal, while short term HSCs do not have this capacity. Short term HSCs, also called progenitor or precursor cells, can differentiate into all types of blood cells, which can be characterized by specific markers. For example, cells that differentiate into lymphocytes and granulocytes can be identified by detecting the expression of certain SLAM family receptors and Integrin alpha M/CD11b, respectively.