Spleen

spleen
(Science: anatomy) An organ that produces lymphocytes, filters the blood, stores blood cells and destroys those that are aging. It is located on the left side of the abdomen near the stomach.
A large dark-red oval organ on the left side of the body between the stomach and the diaphragm; produces cells involved in immune responses.This lymphoid tissue is primarily concerned with blood cells, being the site of production of lymphocytes which regulates the volume of blood cells in the blood stream and removes defective cells. It also actsa as a reservoir for blood and is the site where red blood cells reaching the end of their functional life are broken down.