or macrophage system or mononuclear phagocyte system
Part of the body's defenses, consisting of a class of cells widely distributed in the body.
Reticuloendothelial cells filter out and destroy bacteria , virus es, and foreign substances and destroy worn-out or abnormal cells and tissues. Precursor cells in bone marrow develop into monocytes (see leukocyte ), which are released into the bloodstream. Most enter body tissues, developing into much larger cells called macrophages, with different appearances in various locations. Some roam through the circulation and between cells and can coalesce into a single cell around a foreign object to engulf it. Reticuloendothelial cells also interact with lymphocyte s in immune reactions. Cells in the spleen destroy old red blood cells and recycle their hemoglobin ; uncontrolled, this process causes anemia . Tumour s of the reticuloendothelial system can be localized or widespread throughout the body. See also lymphatic system .