Dr Takeshi IMAI and others at RIKEN Center for Developmental Biology in Kobe have developed a fructose-based solution which rendered mouse embryos and brains transparent within 3 days, permitting observations of fine structures and flurescent labeling under a flurescence microscope without making sections

Meng-Tsen KE et al., Nature Neuroscience 2013,doi: 10.1038/nn.3447