Methods for the Study of NO-Induced Apoptosis in Cultured Cells

In 1972, Kerr et al. (
1
) described a mechanism of cell death that was morphologically distinct from necrosis and they coined the term “apoptosis” [derived from the Greek
apo
(from) and
ptosis
(to fall)], to mean “falling away,” as of leaves from a tree. Although descriptions of cell death consistent with what is now termed apoptosis have been made since 1885 (reviewed in
ref.2
), the importance of this concept has only gained widespread acceptance in recent years. Since 1972, apoptosis has been studied in many cell types and its importance in normal development, tissue mass homeostasis, programmed cell death, and disease is becoming increasingly evident. Unlike necrosis, or accidental cell death, which results from overwhelming damage to a cell making survival impossible, apoptosis is an active, regulated process undertaken by healthy cells in response to appropriate external and internal stimuli, leading to a controlled packaging of the cell contents and, ultimately, death.