Apical bulkhead halves are connected by adherens junctions and sealed by tight junction loops. (a) Left: Schematic model of a BC formed by two adjacent hepatocytes (transparent blue and yellow) in the paradigmatic BC orientation. Right: Visualization of the BC with apical bulkheads from different angles (black arrows) after various cuts of the model (upper) with associated views (lower). (b) Imaging strategy used to visualize the intercellular junctions that connect apical bulkhead halves by STED microscopy. Left: Schematic model of a BC that is tilted 90° compared with the paradigmatic BC orientation. Upper right: The focal plane (light blue rectangle) used for STED microscopy. Lower right: The microscopy view at the cell–cell interface between apical bulkhead halves. (c) Confocal microscopy of a tilted BC between two hepatocytes in vitro, stained for F-actin with phalloidin–AlexaFluor-488 and the tight junction protein Occludin. Scale bar: 10 μm. (d) STED microscopy of Occludin corresponding to the region highlighted in Fig. 1 c. Scale bar: 2 μm. (e and f) STED microscopy of tilted BC between two hepatocytes in vitro stained for the tight junction protein ZO-1 and the adherens junction proteins E-cadherin (e) and β-catenin (f). Scale bars: 5 μm (overview) and 2 μm (zoom). (g) Schematic representation of the tight junctions (cyan) and adherens junctions (magenta) connecting apical bulkhead halves.