Lymphoid tissues are found in all vertebrates and are essential for adaptive immunity. Primary lymphoid tissues (thymus, fetal liver and bone marrow) nurture lymphocyte development, whereas secondary lymphoid organs support lymphocyte maturation, survival and activation.

What is the importance of lymphoid tissues and organs in the body?

The lymphatic system is a subsystem of the circulatory system in the vertebrate body that consists of a complex network of vessels, tissues, and organs. It helps maintain fluid balance in the body by collecting excess fluid and particulate matter from tissues and depositing them in the bloodstream.

What are lymphoid tissues?

The mucosa-associated lymphoid tissue (MALT), also called mucosa-associated lymphatic tissue, is a diffuse system of small concentrations of lymphoid tissue found in various submucosal membrane sites of the body, such as the gastrointestinal tract, nasopharynx, thyroid, breast, lung, salivary glands, eye, and skin.