organs

In secondary or peripheral lymphoid organs, antigen is localized so that it can be effectively exposed to mature lymphocytes. The best examples are lymph nodes, appendix, Peyer’s patches of gastrointestinal tract, tonsils, adenoids, spleen, MALT (Mucosal-Associated Lymphoid Tissue), GALT (Gut-Associated Lymphoid Tissue), BALT (Bronchial/Tracheal-Associated Lymphoid Tissue). Peyer’s patches are oval-shaped areas of thickened tissue that are embedded in the mucus-secreting lining of the small intestine of humans and other vertebrate animals. Peyer’s patches contain a variety of immune cells, including macrophages, dendritic cells, T cells, and B cells.

The tonsils (palatine tonsils) are a pair of soft tissue masses located at the back of the throat (pharynx). The tonsils are part of the lymphatic system, which help to fight infections. They stop invading germs including bacteria and viruses. Spleen is a secondary lymphoid organ located in the upper part of the abdominal cavity close to the diaphragm.

Spleen contains B and T cells. It brings humoral and cell mediated immunity. The adenoids are glands located in the roof of the mouth, behind the soft palate where the nose connects to the throat. The adenoids produce antibodies that help to fight infections.

Typically, the adenoids shrink during adolescence and may disappear by adulthood. Lymph node Lymph node is a small bean-shaped structure and is part of the body’s immune system. It is the first one to encounter the antigen that enters the tissue spaces. Lymph nodes filter and trap substances that travel through the lymphatic fluid.

They are packed tightly with white blood cells, namely lymphocytes and macrophages. There are hundreds of lymph nodes found throughout the body. They are connected