Koch, UteRadtke, Freddy2012-06-252012-06-25201110.1146/annurev-cellbio-092910-154008https://infoscience.epfl.ch/handle/20.500.14299/82146WOS:000299230700021T cells are the key mediators in cell-mediated immunity. Their development and maturation involve a complex variety of interactions with nonlymphoid cell products and receptors. Highly specialized to defend against bacterial and viral infections, T cells also mediate immune surveillance against tumor cells and react to foreign tissues. T cell progenitors originate in the bone marrow and, through a series of defined and coordinated developmental stages, enter the thymus, differentiate, undergo selection, and eventually mature into functional T cells. The steps in this process are regulated through a complex transcriptional network, specific receptor-ligand pair interactions, and sensitization to trophic factors, which mediate the homing, proliferation, survival, and differentiation of developing T cells. This review examines the processes and pathways involved in the highly orchestrated development of T cell fate specification under physiological as well as pathological conditions.cell fate specificationhoming receptorsNotch signalingT cell acute lymphoblastic leukemia (T-ALL)Acute Lymphoblastic-LeukemiaCommon Lymphoid ProgenitorsBeta-Selection CheckpointB Lineage DecisionTcr-Gamma-LocusDelta-Like 4Bone-MarrowStem-CellsHematopoietic ProgenitorsAlpha-Betatext::journal::journal article::review article