Resinous mounting media have an index of refraction much lower than tissue.

• A. True
• B. False
• C. Sometimes true
• D. Not applicable

Answer: (B)

Understanding how light passes through tissue and its surroundings helps explain this. The refractive index of resinous mounting media is chosen to be close to that of tissue (and glass), so light passes with minimal bending at the interfaces. Resinous media typically have refractive indices around 1.52–1.54, which is similar to the refractive index of most biological tissues. If the mounting medium were much lower in index than tissue, there would be greater light refraction and scattering at the tissue-media boundary, reducing image clarity. Since resinous mounting media are matched rather than significantly lower, the statement is false.