Final answer:
Pyknosis is indicative of a condensed cell nucleus, often associated with apoptosis, and results in the nucleus appearing small and darkly stained.
Step-by-step explanation:
Pyknosis indicates a condensed cell nucleus. This is a process associated with the apoptosis (programmed cell death), where the cell's nucleus shrinks and the chromatin condenses. One of the hallmarks of pyknosis is a small, dark staining nucleus because the chromatin becomes highly condensed.
It should not be confused with other cellular changes such as the formation of vacuoles, fusion of cytoplasmic membranes, or the presence of inclusion bodies which are different and specific pathological or physiological conditions affecting cells.