Sequence of 3 false-colour scanning electron micrographs showing a macrophage, a type of white blood cell, approaching, engulfing, & consuming a red blood cell in the process of phagocytosis. Red blood cells, or erythrocytes, lack the usual cellular apparatus for self-repair. As a result, they live on average 120 days, & are then consumed by macrophages or white cells called neutrophils. What signals the white cell to move in is unknown, although the red cell's ability to maintain its normal biconcave shape may be involved. The red cell here has become spherical. New red blood cells are constantly manufactured in the body. (Magnification unknown). Ref: Microcosmos, fig. 2.45, page 38.