Tissue clearing refers to a group of chemical techniques used to turn tissues transparent.This allows deep insight into these tissues, while preserving spatial resolution. Many tissue clearing methods exist, each with different strengths and weaknesses. Some are generally applicable, while others are designed for specific applications. Tissue clearing is usually combined with one or more labeling techniques and subsequently imaged, most often by optical sectioning microscopy techniques.Tissue clearing has been applied to many areas in biological research.
Principles Tissue opacity is thought to be the result of light scattering due to heterogeneous refractive indices. Tissue clearing methods chemically homogenize refractive indices, resulting in almost completely transparent tissue.