What principal property should mounting media have in terms of refractive index?

The principal property that mounting media should have is that its refractive index should be close to that of glass and the tissue being examined. This similarity is crucial because it minimizes light refraction at the interfaces where the media, glass, and tissue meet. When the refractive indices are closely matched, it allows for better visibility and clarity of the specimen, as it reduces light scattering and allows more light to pass through efficiently.

In microscopy, achieving optimal image quality depends significantly on the clarity with which light can travel through different materials. If the refractive index of the mounting media is too dissimilar to that of the tissue or the glass slide, it can lead to distortions, making the specimen harder to view correctly. Therefore, using a mounting medium with a refractive index similar to both glass and tissue enhances contrast and improves the overall visual fidelity of the sample under observation.