T-Cell Differentiation

**Semantic type:** Cell Function

**Definition:** Development of bone marrow-derived stem cells in the thymus through stages of positive selection under the influence of epithelial cells in the thymic cortex and negative selection under the influence of bone marrow-derived dendritic cells at the corticomedullary junction. Thymic T cell precursors (thymocytes) progress through phases expressing both CD4 and CD8 coreceptors to a single positive stage expressing only CD4 or CD8 in addition to the T cell receptor. They are then allowed to leave the thymus and enter the periphery via the lymphatics or venules of the circulatory system as mature T cells. (NCI/OSP)

**Synonyms:** - T-Cell Development - T-Cell Ontogeny - T-Lymphocyte Development