Assays of Apoptosis

The phenomenon of apoptosis has gone from obscurity in 1972, when it was named (1 ), to the limelight of over 6000 publications in 1998 alone. Originally described as a peculiar morphology of cell death, seen when that death was “physiological” or programmed, apoptosis remains most clearly determined by morphology. Although there has been a great deal of interest in the biochemical and genetic regulation of the process, there is still no molecular definition of apoptosis for which a counterexample cannot be found. Thus in this chapter we have focused on morphology. The techniques we describe have the further virtue of being relatively inexpensive with respect to both reagents and equipment. We assume here that the investigator wants to determine whether the cells of interest have died by apoptosis or necrosis; if this question is not important, then any of the common dye-exclusion methods can be used to distinguish live from dead cells.