Posted by jayaram in Structure of spleen
Spleen is the largest lymphoid organ in the body and it is highly vascular. It is situated in left hypochondrial region. An outer serous coat and an inner fibro muscular capsule cover the spleen. From the capsule, the trabeculae and trabecular network arise. All the three structures capsule, trabeculae and trabecular network contain collagen fibers, elastic fibers, smooth muscle fibers and reticular cells. The parenchyma of spleen is arranged in the form of red pulp and white pulp.
Red pulp
This consists of venous, sinus and cords of structures like blood cells, macrophages and mesenchymal cells.
White pulp
The structure of white pulp is similar to that of lymphoid tissue. It has a central artery, which is surrounded by splenic corpuscles or malpighian corpuscles. The lymphatic sheath containing lymphocytes and macrophages forms these corpuscles.
Function of spleen
Formation of blood cells
The spleen plays an important role in the hemopoietic function in embryo. During the hepatic stage, spleen produces the blood cells along with liver. In myeloid stage, it produces the blood cells along with liver and bone marrow.
Destruction of blood cells
The older red blood cells, lymphocytes, and thrombocytes are destroyed in the spleen. When the red blood cells become old 120 days, the cell membrane becomes more and more fragile. The diameter of the capillaries is less or equal to that of red blood cell. When these cells try to squeeze through the capillaries, these are destroyed. The destruction occurs mostly in the capillaries of spleen because; the splenic capillaries have a thin lumen. So, the spleen is known as the graveyard of red blood cells.