Pap smears must be placed in 95% alcohol for 15 minutes before staining to prevent what?

• A. Nuclei from appearing foggy and lacking detail
• B. Color alteration during staining
• C. Sample contamination
• D. Overfixation of tissue

Answer: (A)

Fixation with 95% alcohol in Pap smears preserves cellular structure, especially nuclear detail, by rapidly immobilizing cellular components and preventing air-drying artifacts. This keeps the nuclei crisp and sharply defined so the chromatin pattern stains clearly with hematoxylin and the subsequent cytoplasmic dyes. If fixation is inadequate or the smear dries before fixation, nuclei tend to blur and look foggy, making it hard to assess cellular details. The 15-minute alcohol fixative provides enough stabilization without the risk of overfixation that longer exposures might cause in tissue sections. Color changes during staining and contamination are addressed by other steps in the protocol and are not the primary reason for this fixation.