• The normal adult spleen weighs 150–250g and is 5–13cm in diameter.
• It has a specialized circulation because the majority of arterioles end in ‘cords’ which lack an endothelial lining. The blood re‐enters the circulation via venous sinuses. The cords and sinuses form the red pulp which monitors the integrity of red blood cells.
• The central arterioles are surrounded by lymphoid tissue called white pulp which is similar in structure to a lymph node.
• The spleen removes aged or abnormal red cells, and excess DNA and siderotic granules, from intact red cells. It also has a specialized immune function against capsulated bacteria, Pneumococcus, Hemophilus influenzae and Meningococcus, against which splenectomized patients are immunized. Splenectomy is needed for splenic rupture and in some hematological diseases.