phatic organs. Lymphocytes differentiate into immunocompetent cells in these organs. Initially, lymphocytes are genetically programmed to recognize a single antigen out of virtually an infinite number of possible antigens, a process called antigen-independent proliferation and differentiation. These immunocompetent cells then enter the blood or lymph and are transported throughout the body, where they are dispersed in the connective tissue.

Lymphocytes undergo antigen-dependent activation in the secondary lymphatic organs

Immunocompetent lymphocytes (together with plasma cells derived from B lymphocytes and with macrophages)

organize around reticular cells and their reticular fibers to form the adult effector lymphatic tissues and organs, i.e., lymphatic nodules, lymph nodes, tonsils, and spleen. Within these secondary or peripheral lymphatic organs, T and B lymphocytes undergo antigen-dependent activation into effector lymphocytes and memory cells.

0 0

Post a comment