Dying liver cells. Scanning electron micrograph (SEM) of two liver cells (hepatocytes) undergoing apoptosis, or programmed cell death. The cells have been treated with the chemical hydrazine (rocket fuel), which has caused them to self- destruct. Apoptosis is characterised by membrane blebbing (swelling), as shown here, cell shrinkage, and the fragmentation of a cell's DNA (deoxyribonucleic acid). Apoptosis ensures that the leakage of a dying cell's harmful constituents is minimised. The packaged fragments of the dead cell will be engulfed and digested by the body's phagocytic cells. Magnification: x 1800 when printed at 10 centimetres.