Author response image 3. Equivalent tomographic slices of brush border regions of gut epithelial cells from wild-type mice that were optimally preserved for EM imaging by high-pressure freezing/freeze substitution (HPF/FS) fixation (left) or optically cleared using CLARITY prior to HPF/FS (right).
Clearing caused drastic loss of ultrastructural detail, likely due to extraction of lipids from the tissue (Term. web = terminal web; ICS = intercellular space).