thymus gland

a GLAND , divided into two lobes, that is present in the neck and forms a vital part of the body's response to INFECTION . It is especially large in children and important in the development of the IMMUNE response and the production of lymphoid tissue. After PUBERTY , it gradually begins to shrink. BONE MARROW cells, known as stem cells, undergo maturation within the thymus, and one group, the T-LYMPHOCYTES , are dependent on the gland. These are very important cells in the body that produce ANTIBODIES .