ABSTRACT
Cell death is an irreversible loss of structure and function. Cells die primarily by one of two major mechanisms, that is, by necrosis or apoptosis. Cell death by necrosis occurs as a result of a marked toxic or physical insult. For many years, cell death had been synonymous with necrosis and felt to be a result of massive tissue damage and widespread cell injury, often following exposure to high concentrations of chemicals. The biochemical hallmark of apoptosis has been considered to be the internucleosomal cleavage of DNA into nucleosomal fragments of 180 to 200 base pairs or multiples thereof. The most distinctive biochemical characteristic of apoptosis is the “DNA ladder” observed on agarose gel electrophoresis. A wide variety of diverse agents have been shown to induce apoptosis in many different systems. One of the best characterized model systems is the induction of apoptosis in thymocytes.
