Lymphoid Organs

Primary (central) lymphoid organs

Primary (central) lymphoid organs

Organs where lymphocytes are produced and mature, including the bone marrow and thymus.

Bone marrow

Soft, spongy tissue found in the center of bones, responsible for the production of blood cells.

Thymus

A gland located in the chest that is involved in the development and maturation of T-lymphocytes.

Lymph nodes

Small, bean-shaped organs found throughout the body that filter lymph and contain immune cells.

Cortex (lymph nodes)

The outer region of a lymph node, containing lymph nodules/follicles and cortical lymph sinuses.

Medulla (lymph nodes)

The inner region of a lymph node, containing medullary cords and medullary sinuses.

Spleen

An organ located in the upper left abdomen that filters blood and plays a role in immune responses.

Red pulp (spleen)

The region of the spleen involved in filtering and removing old or damaged red blood cells.

White pulp (spleen)

The region of the spleen involved in immune responses, containing lymphocytes and specialized structures called PALS.

MALT

Mucosa-associated lymphoid tissue, a diffuse system of lymphoid tissue found in the mucosal linings of various organs.