False-colour transmission electron micrograph (TEM) of a maturing eosinophil from human bone marrow. Eosinophils, with neutrophils & basophils, comprise a group of white cells termed granulocytes. In their formation (granulopoiesis), stem cells differentiate & mature to ultimately produce the various sub-types. Granulocytes are released into the circulation at maturity, with a large reserve of immature cells retained in the marrow. Characteristic of an eosinophil is a bilobed nucleus (blue & purple), with a cytoplasm (green) packed with granules (red). Magnification: x7200 at 6x7cm size.