Apoptosis

Synonyms

Programmed Cell Death; Active Cell Death

Definition

Apoptosis is a T cell death process that occurs during development and aging of animals and humans. It is also induced by cytotoxic lymphocytes (CTL), anti-cancer drugs, γ- or UV-radiation, a group of cytokines called death factors and deprivation of survival factors.

Characteristics

Apoptosis was initially characterized by morphological changes of dying cells. During apoptosis cells shrink, and microvilli on the plasma membrane disappear. The nucleus is also condensed and fragmented. At the final stage of apoptosis the cells themselves are fragmented with all cellular contents inside. One of the biochemical hallmarks of apoptosis is the fragmentation of chromosomal DNA into nucleosome size units (180 bp).

Apoptotic cells can be recognized by staining of the condensed nuclei with fluorescence dyes Hoechst or DAPI. Apoptotic cells expose phosphatidyl-serine to the cell surface, which can be stained with