Tetrahydrofuran is a universal solvent, causes diffusion currents that can harm delicate tissue morphology in small specimens such as lung biopsy. What is a key drawback of using THF?

• A. It is a good staining solvent
• B. It can harm delicate tissue morphology in small specimens
• C. It fixes tissue more strongly
• D. It preserves tissues perfectly

Answer: (B)

THF’s main issue in tissue processing is its rapid diffusion and evaporation, which can physically disturb delicate tissue architecture. As a transitional solvent, THF readily exchanges with surrounding solvents and with paraffin. In small specimens, like lung biopsy, these quick solvent movements create diffusion currents that can tug on cells and collapse or blur fragile structures, producing distorted morphology. This makes THF a drawback despite its usefulness as a solvent for infiltration. It isn’t a staining solvent, it doesn’t fix tissue, and it doesn’t preserve tissues perfectly; those roles are filled by staining reagents and fixatives, not THF.