Pig spleen. Spleen is the largest immune organ in the body, located in the left upper abdomen, accounting for 25% of the total lymphoid tissue. It contains a large number of lymphocytes and macrophages, and is the center of cellular immunity and humoral immunity. It is located in the depth of the posterolateral rib arch in the left-season rib area, opposite to the 9- 1 1 rib, and its long axis coincides with the 10 rib. Diaphragm is adjacent to diaphragm and left costal diaphragm sinus, stomach is in front, left kidney and left adrenal gland are in back, and the lower end is adjacent to colon and splenic groove. Adult spleen is about 10 cm ~ 12 cm long, 6 cm ~ 8 cm wide, 3 cm ~ 4 cm thick and weighs 165438. In the upper abdomen. Under normal circumstances, the spleen is untouchable. If you can touch the edge of the spleen in supine or right lateral position, it means splenomegaly.