Where does the maturation of T-lymphocytes take place?

The immune system of jawed vertebrates uses lymphocytes, which are white blood cells. Natural killer cells, T cells, and B cells are lymphocytes that perform cell-mediated, cytotoxic innate immunity, cell-mediated, cytotoxic adaptive immunity, and cell-mediated, cytotoxic innate immunity (for humoral, antibody-driven adaptive immunity). The term "lymphocyte" comes from the fact that they are the most common type of cell found in lymph. Lymphocytes, commonly known as leukocytes, make about 18 to 42 percent of all circulating white blood cells.

The thymus gland or lymph nodes are where T-cells mature. The lymph nodes have a larger role in the maturation process than the thymus, which is only 10-15% functioning in adults. T cells moving from the bone marrow to the Thymus gland will go through a selection process to eliminate not just the weakest cells, but also those that are powerful enough to target healthy tissue cells (autoimmunity). Helper (CD4+) or Suppressor/Cytotoxic (CD8+) cells are the most common cells educated in the Thymus. T-helper 17, T regulatory cells, and T follicular helper cells are examples of other T-helper cell types. 

Dendritic cells that have internalized and manufactured pathogenic antigens that have made their way to the lymph node via lymphatic drainage from the area of inflammation or dendritic cells that have migrated to the lymph node from the site of infection, have the ability to activate naive T cells in the paracortex of the lymph node. T cells go through clonal expansion after activation and develop into functional (short-lived) or memory effector cells (long-lived). Functional effector cells migrate to the site of infection or inflammation to orchestrate T helper (CD4+) or T cytotoxic/suppressor (CD8+) functions in order to battle infections. Memory cells have the ability to leave the lymph node and enter the circulation or other healthy tissue sites. They may also stay for a long time in the lymph node.