In our body, the blood bank is spleen. The spleen is the largest solid mass of reticulo-endothelial tissue in the body. It is covered by a capsule formed of elastic fibrous connective tissue and smooth muscles. The main function of spleen in adult is its sinuses act. as reserviors of blood. When required, their blood is squeezed into general circulation. Similarly, the red blood corpuscles stored in spleen are released into general circulation. When required many lymphocytes of spleen produces antibodies.