Nuclear bubbling is caused by incomplete fixation.

• A. Incomplete fixation
• B. Overfixation
• C. Dehydration failure
• D. Oxygen exposure

Answer: (A)

Fixation quality directly preserves nuclear structure by cross-linking proteins and stabilizing chromatin. When fixation is incomplete, the nuclear envelope and nucleoplasm aren’t properly stabilized, so during processing the nucleus can develop vesicle-like spaces or bubbles as membranes and contents separate or autolyze. This appearance is the nuclear bubbling artifact, signaling inadequate fixation. Overfixation, dehydration problems, or oxygen exposure don’t produce this specific nuclear bubble pattern: overfixation tightens cross-links and can dull staining, dehydration failures cause poor infiltration, and oxygen exposure isn’t the culprit here.