Clarity and related tissue clearing methods

A major breakthrough in tissue processing for fluorescent tissue imaging was published in 2013 by Chung et al. from the Stanford lab of Karl Deisseroth. These authors realized that when tissues are fixed for processing for immunological staining the fixative reagents bind and cross link primarily protein side chains, leaving lipids unaffected. So it should be possible to fix a tissue and elute out the lipids which, if feasible would have many advantages. Lipid membranes make tissues opaque so microscopy, so microscopy of cleared tissues would be improved, particularly in the case of thicker samples. Another significant advantage is that the membranes present a significant barrier to antibody entry, so cleared tissues can be stained more quickly and completely then non-cleared tissues. This paper showed how electrophoresis of fixed brain tissue in the presence of SDS detergent could be processed to remove lipid following stabilization of the brain tissue with polyacrylamide. The paper generated enormous interest and numerous variants of the basic method have been published. We have usd the original technique