Apotome microscope axioimager z1

At the end of the experiment, animals were overdosed with urethane (3 g/kg), transcardially perfused with paraformaldehyde 4 % (V/V in phosphate buffer) and their brains were removed and prepared for flattened corticotangential sectioning, as described by Lauer et al., (2018) (link). Cortical sections were stained for cytochrome oxidase, and layer IV barrel-field cytoarchitecture was visualized under bright-field light microscopy. Mystacial pads were dissected, cryoprotected in a 0.1 M phosphate buffer solution containing 30% sucrose (w/v) and cut into 50 µm thick transversal sections with a cryostat microtome (CM3050S; Leica Biosystems, Wetzlar, Germany). Sections were counterstained with the nuclear dye 4′,6-Diamidine-2′-phenylindole dihydrochloride (DAPI; Sigma-Aldrich, Germany) and actin filaments were labeled with the fluorescent conjugate ATTO 647-phalloidin (Hypermol EK, Bielefeld, Germany). Optical sections of the whisker follicle-sinus complex were acquired by confocal-like optical sectioning with an Apotome Microscope (Axioimager Z1; Carl Zeiss Microscopy GmbH, Jena, Germany). The expression of TeNT-GFP in Cre-positive mice was confirmed by the presence of a green fluorescence signal in the MC-dense region of the whisker FSC.