chung and deisseroth cite this article in their review "Light microscopy mapping of connections in the intact brain" (SVSNEURO also mentioned it in another discuccion):
A Method for 3D Immunostaining and Optical Imaging of the Mouse Brain Demonstrated in Neural Progenitor Cells" Plos One 8, Published: August 06, 2013 DOI:10.1371/journal.pone.0072039 Jacqueline A. Gleave, Jason P. Lerch, R. Mark Henkelman, Brian J. Nieman
in this article they treat the tissue with a freeze-thaw cycle, ending with a short incubation in proteinase K. they report antibody staining of 1 mm thick tissue samples.
at 1 hour 8 minutes into this lecture deisseroth talks about achieving deeper antibody oenetration,
he mentions that they have started using both proteinase K, and a lower concentration of bis in the monomer-solution, to reduce the cross-linking extent.
has anyone of you guys experimented with proteinase K, lower bis-concentration, or any other protocols in order to achieve deeper antibody penetration?