Osmosis video - Spleen histology

The spleen is an essential part of the immune system, which is also responsible for filtering blood and removing damaged or old red blood cells. At a gross level, the spleen's parenchyma consists of red pulp, with small white nodules of lymphatic tissue scattered throughout called the white pulp. The red pulp has sinusoids, splenic cords, and macrophages, and plays a major role in removing old and damaged red blood cells.

The white pulp, which is involved in immune function, is arranged in spherical nodules called splenic nodules surrounded by a sheath of lymphoid tissue known as the periarteriolar lymphoid sheath (PALS). Within the splenic nodules are two types of lymphoid tissue: the follicles and the marginal zone. The follicles contain B-lymphocytes, whereas the marginal zone contains a mixture of B-lymphocytes, T-lymphocytes, and macrophages.