Neutrophil. Artwork based on an electron micrograph showing a neutrophil white blood cell. Neutrophils also known as polymorphonuclear white blood cells or polymorphs have large, highly lobulated nuclei (cream/blue). Their cytoplasm (pale blue) contains large digestive lysosomes (purple/blue). Neutrophils protect the body from infection by engulfing and digesting invading microorganisms by phagocytosis. These highly mobile cells migrate to areas of tissue damage. However, after a burst of activity they degenerate, as the enzymes they use quickly become depleted. Defunct neutrophils form the majority of pus.