Caption

False-colour transmission electron micrograph (TEM) of a human macrophage (left, green cell with blue nucleus) phagocytosing (engulfing) an eosinophil, a white blood cell. Three free eosinophils are visible at right. Macrophages are active in tissues, migrating to sites of infection in response to chemical stimuli. In addition to a scavenging role, the macrophage is capable of processing antigenic substances during the initial phase of immune response. Processed antigens are presented on the macrophage's surface for recognition & elimination by certain lymphocctes. Magnification: x3400 at 6x7cm, x1700 at 35mm size.