As programmed cell death (PCD), or apoptosis, has emerged as an important 
regulator of development and homeostasis in multicellular organisms, methods to 
quantify apoptosis and to distinguish it from necrosis have been developed. 
Necrosis refers to the morphology usually associated with accidental cell death, 
while apoptosis is seen when cell death is programmed or physiologically 
regulated. This unit presents a set of assays for these purposes, many of which 
are technically very simple. Featured in this unit is the TUNEL method of 
detecting cells that exhibit DNA fragmentation, which can also be performed on 
tissue sections to locate apoptotic cells in situ.