If there is no secondary
necrosis (that happens in the late stage), the cellular
membrane is always intact. Hence, the apoptotic cells
at the early stage are not stained with propidium iodide,
but the Hoechst dye is positive. However, the diagnostic
finding in these cells is the nuclear morphology, which
should show some specific appearances for apoptosis as
explained above. Therefore, typical nuclear fragmentation
or the chromatin condensation is the most important
feature for apoptotic cell death.