Apoptosis. Coloured scanning electron micrograph (SEM) of a brain cancer cell in the early stages of programmed cell death, or apoptosis. Apoptosis occurs when a cell becomes old or damaged. The cell becomes spherical as its cytoskeleton, which holds cell shape, is digested, and blebs (vesicles pink) form on its surface. Eventually the cell breaks into several vesicles, now known as apoptotic bodies, and is phagocytosed (engulfed and digested) by specialist cells. The breakdown into vesicles prevents the leakage of potentially toxic or immunogenic substances from the cell. Magnification: x6000 when printed at 10 centimetres wide.