The problem is the result of which artifact?

• A. Air trapped under the section
• B. Cracks in tissue
• C. Overhydration
• D. Contamination

Answer: (A)

Air trapped beneath a tissue section creates voids where the tissue is not in contact with the slide, so those areas don’t stain properly and the section may appear lifted or have bubble-like gaps. This explains a visible problem as gaps or clear spaces within the tissue on the slide, which is characteristic of air bubbles under the section. Cracks in tissue show as fine lines or breaks, overhydration makes tissue swell and blur boundaries, and contamination appears as foreign particles or debris—none of which produce those distinct empty spaces caused by trapped air. Prevent by ensuring the section adheres well to the slide, drying thoroughly before mounting, using appropriate mounting medium, and placing the coverslip carefully to push out any air.