Table 3.

Comparison of different refractive index matching solutions

Reagent	Fluorescent signal preservation	Transparency	Time to maximal clearance (3 × 3 × 3 mm3 tissue block)	Preparation	Storage	Other remarks
PBST	Good	+	Never	Simple	Indefinitely	N/A
FocusClear	Good	+++	2 h	(Bought)	Cannot be stored	Occasional yellow precipitates or discoloration observed
87% Glycerol	Good	++	Overnight	Simple	Not recommended, slight loss of signal after 2 days	Cheapest and simplest
BABB	Poor	++	3 h	Simple but hazardous	Cannot be stored	Over‐shrinkage
Histodenz‐RIMS	Moderate in humans, good in mice	+++	Overnight	Complex	Up to 6 months for mice, up to 1.5 months for humans	Works best for mice brains
Sorbitol (sRIMS)	Good	+++	Overnight	Complex	Up to 6 months for mice, up to 1.5 months for humans	Take extra care to avoid fungal growth
SeeDB	Moderate	++	6 h	Complex	Up to 1.5 months for humans	Take extra care to avoid fungal growth
ScaleA2	Good	++++	3 h	Simple	Up to 1.5 months for humans	Tissue remains swollen/swells even more; most transparent
THF/DBE	Moderate	++	18 h	Simple but hazardous	Up to 1.5 months for humans	Over‐shrinkage
47% TDE in PBS	Good	++++	3 h	Simple	Up to 1.5 months for humans	Remains slightly swollen
63% TDE in PBS	Good	+++	3 h	Simple	Up to 1.5 months for humans	Shrinks back to original size

BABB, benzyl alcohol–benzyl benzoate; DBE, dibenzyl ether; PBS, phosphate‐buffered saline; PBST, phosphate‐buffered saline with Triton‐X; RIMS, refractive index matching solution; TDE, 2,2′‐Thiodiethanol; THF, tetrahydrofuran.