Practical assessment of morphological changes associated with programmed
cell death or apoptosis relies in practice on light microscopy. Examination of
tissue sections should include looking for pycnotic cells or apoptotic bodies,
looking for histological evidence of nuclear fragmentation, using dyes and
internucleosomal DNA cleavage, using TUNEL staining, and other screening
methods for cell death and tissue reaction. These approaches are quite reliable
in most defined experimental contexts for detecting and quantitating cell death.
For routine screening and assessment, light microscopy is to be preferred for
the rapid ability to survey large areas. However, in new experimental paradigms
or complex tissues with multiple cell classes, adequate documentation
of the cellular changes of apoptosis must also be based on ultrastructural
demonstration of characteristic features of apoptotic cell death.