Apoptosis: the complex scenario for a silent cell death.

In multicellular organisms, homeostasis is maintained by a balance between cell proliferation and apoptosis (programmed cell death). It is a physiological form of cell death responsible for the deletion of not reparable damaged, mutated, or cells which have lost their function. Apoptosis can be distinguished by morphological and biochemical characteristics from necrosis (pathological cell death). Apoptotic cell death does not disturb surrounding cells. To achieve the elimination of cells without an inflammatory reaction, a complex interplay of several molecules is necessary. Apoptosis either starts from the cell surface (CD95-CD95L), the mitochondrion or from the nucleus. The cell biological events run in a cascaded fashion and are regulated by either enhancer or anti-apoptotic signals that probably may stop the executions machinery. The knowledge about apoptosis helps to understand pathophysiologic conditions, to better diagnose and treat them by molecular radiological techniques.