AP BIOLOGY

Detailed explanation-1: -The thymus is the primary lymphoid organ where lymphocytes originate and/or mature. T-lymphocytes originate from lymphoid progenitor cells in thymus via three developmental stages, namely pro, pre and immature T cells. The immature T cells mature in thymus only.

Detailed explanation-2: -The thymus is divided into two main regions, a peripheral cortex and a central medulla (see Fig. 7.7). Most T-cell development takes place in the cortex; only mature single-positive thymocytes are seen in the medulla.

Detailed explanation-3: -The primary function of the thymus gland is to train special white blood cells called T-lymphocytes or T-cells. White blood cells (lymphocytes) travel from your bone marrow to your thymus. The lymphocytes mature and become specialized T-cells in your thymus. After the T-cells have matured, they enter your bloodstream.

Detailed explanation-4: -Key Points. Hematopoietic progenitors derived from hematopoietic stem cells populate the thymus and expand by cell division to generate a large population of immature thymocytes. After the thymus becomes inactive later in life, existing immature T cells will proliferate through clonal expansion.

Detailed explanation-5: -T cells originate in the bone marrow and mature in the thymus. In the thymus, T cells multiply and differentiate into helper, regulatory, or cytotoxic T cells or become memory T cells.