White blood cells. Coloured scanning electron micrograph (SEM) of polymorphonuclear white blood cells (leucocytes). Polymorphonuclear leucocytes are any of several types of white blood cells produced in bone marrow, including neutrophils. They form 60-70% of human white blood cells. Here rounded in shape, they have protuberances on their surface which enables them to be motile. Inside they have a granular cytoplasm and a bilobed nucleus. Polymorphonuclear leucocytes play an important role in the immune system. They are predominantly phagocytic, migrating to areas of tissue damage and engulfing foreign bodies such as bacteria. Magnification x9,000 at 6x7cm size. Magnification: x30,000 at 8x10 inch size.