As hematoxylin stains chromatin, apoptotic cells
are evaluated according to nuclear morphology.
Changes that are specific for apoptosis may easily
be observed if the staining was well performed.
However, experience is needed, since the
mitotic cells at the early stages (e.g. prophase or
metaphase) may be confused with apoptotic cells
in some instances. The following may be observed
in the apoptotic cells: cellular shrinkage,
chromatin condensation and its accumulation at
the periphery of the nuclear membrane, pyknosis
or nuclear fragmentation. In figure 1a, the nuclear
fragmentation and chromatin condensation
can be observed. In untreated cells several mitotic
cells are also visible in different stages of the
cell cycle