ABSTRACT
Tissue optical clearing techniques have provided important tools for large-volume imaging. Aqueous-based clearing methods were known for their good fluorescence preservation and scalable size maintenance, but many of them were limited by a long incubation time, which greatly hindered their wide application in biological research. To shorten the clearing time, different methods have been proposed aiming at multiscale tissues, including hundred-micron-thin tissue slices, several-millimeter-thick tissue blocks, adult whole organs, and even whole bodies. To achieve ultrafast clearing, some clearing methods screened different chemical mixtures, such as FOCM, ClearT/T2, RTF, ScaleSQ, and MACS; and others modified the clearing conditions, such as the ACT method. This chapter introduces these ultrafast aqueous clearing protocols from the angle of their applicability in tissues with different scales. These rapid aqueous clearing protocols are expected to contribute to certain research areas, including high-throughput analysis of morphology and even urgent clinical diagnosis, providing powerful alternatives for speedy clearing.
