uDISCO

uDISCO is a solvent-based tissue clearing method designed to render whole organs and intact adult mice optically transparent for three-dimensional fluorescence imaging. It is part of the DISCO family and represents an optimized variant intended to preserve endogenous fluorescence and reduce tissue distortion compared with earlier clearing approaches.

The protocol generally involves dehydration of the specimen with a graded organic solvent series, commonly including tert-butanol, to remove water and lipids, followed by immersion in a refractive index–matching clearing solvent such as dibenzyl ether. The refractive index matching minimizes light scattering, enabling deep imaging with light-sheet or confocal microscopy.

Key features of uDISCO include the ability to clear whole-body samples or large organs and to retain fluorescence from endogenous reporters (for example GFP variants) with relatively good signal preservation. It tends to produce less shrinkage than some older solvent-based methods, though some distortion can still occur. Clearing times can range from days to weeks depending on sample size, and the technique requires careful handling of volatile, toxic solvents.

Applications span neuroanatomy, vascular and organ-wide imaging, and structural studies in intact mice, enabling researchers to visualize complex cellular networks in 3D without sectioning. Limitations include toxicity and safety concerns due to organic solvents, the need for specialized imaging equipment and mounting, and limited compatibility with immunolabeling compared with immunolabeling-focused methods such as iDISCO. Overall, uDISCO provides a rapid, high-clarity option for whole-organ and whole-animal imaging in fluorescence-based studies.