"Programmed cell death" has been found in many multicellular organisms and occurs as a part of normal development as well as in pathological processes associated with some diseases. Programmed cell death, or apoptosis, is the process whereby certain cells are induced to activate their own death or cell suicide. Apoptosis has been described in a wide variety of cell and tissue types from nematodes to mammals. Apoptosis, unlike necrosis, is mediated by the active participation of dying cells. In another words, the dying cells synthesize certain proteins and enzymes to carry out the "suicide" process. The genes involved in apoptosis have been defined in animals as well as in plants. Some of these genes act as inducers while the others as inhibitors. It has been found that apoptosis related genes have high homology in terms of DNA sequences, suggesting the occurence of an evolutionarily preserved common programmed cell death mechanism among multicellular organisms. The possible role of apoptosis may be related to the regulation of normal development as in animals or it may be involved in defense responses against pathogens as in hypersensitive response (HR) in plants.

"Programmed cell death" has been found in many multicellular organisms and occurs as a part of normal development as well as in pathological processes associated with some diseases. Programmed cell death, or apoptosis, is the process whereby certain cells are induced to activate their own death or cell suicide. Apoptosis has been described in a wide variety of cell and tissue types from nematodes to mammals. Apoptosis, unlike necrosis, is mediated by the active participation of dying cells. In another words, the dying cells synthesize certain proteins and enzymes to carry out the "suicide" process. The genes involved in apoptosis have been defined in animals as well as in plants. Some of these genes act as inducers while the others as inhibitors. It has been found that apoptosis related genes have high homology in terms of DNA sequences, suggesting the occurence of an evolutionarily preserved common programmed cell death mechanism among multicellular organisms. The possible role of apoptosis may be related to the regulation of normal development as in animals or it may be involved in defense responses against pathogens as in hypersensitive response (HR) in plants.