Review on mechanisms of regulating apoptosis in animal cells

In normal tissues, cell proliferation is generally restricted to cells that replenish the tissue. Cell number is dependent not only on cell proliferation, but also on cell death. Apoptosis is the process by which excess or damaged cells in the body are removed. This is an energy dependent a synchronic process that comprises the loss of cell-to-cell contacts, cytoplasmic shrinkage, membrane blebbing, DNA fragmentation, disassembly of the nuclei and formation of apoptotic bodies. The mechanism of apoptosis is highly complex and involves energy dependent cascade of molecular events. It is mediated mainly through three pathways: extrinsic, intrinsic and perforin pathway. The apoptotic mode of cell death is an active and defined process which plays an important role in the development of multicellular organisms and in the regulation and maintenance of the cell populations in tissues upon physiological and pathological conditions. Proper function of the apoptotic machinery is of fundamental importance during the growth and development of the organism, because apoptosis in accord with cell division ensures the proper shaping and the structural and functional integrity of the various tissues and organs. Morphological features of apoptosis can be detected by various cytochemical and microscopic methods.