ReviewAdvances and perspectives in tissue clearing using CLARITY

•Recent developments of CLARITY-based tissue clearing protocols are reviewed.•Improvements to the protocol have proved successful in many types of tissues and species.•The protocol has significantly been improved regarding clearing and staining speed.•While considerable progress has been made, challenges remain. We discuss the prospects.

CLARITY is a tissue clearing method, which enables immunostaining and imaging of large volumes for 3D-reconstruction. The method was initially time-consuming, expensive and relied on electrophoresis to remove lipids to make the tissue transparent. Since then several improvements and simplifications have emerged, such as passive clearing (PACT) and methods to improve tissue staining. Here, we review advances and compare current applications with the aim of highlighting needed improvements as well as aiding selection of the specific protocol for use in future investigations.