WPBs stay connected to the Golgi until vesicle formation is completed. WPBs 8 hours after transfection localized by CLEM and analyzed by electron tomography. (A) Two-dimensional image of 3 supposedly individual WPBs (asterisk) in close proximity to the Golgi. (B-Bi) Tomogram sections that reveal the continuous membrane around an irregular-shaped WPB, which is formed by 3 parts (asterisk) indicated in A. (C-E) Tomogram sections showing the connections (arrows) between the Golgi and the WPB. (Ci-Ei) Zoom of the connections (arrows) shown in C-E. See also supplemental Video 2. Scale bars: (A) 1 µm; (B-Bi and C-E) 500 nm; (Ci-Ei) 100 nm. Electron micrographs and tilt series for tomography were acquired using an FEI Tecnai 12 at 120 kV and using an FEI Eagle 4k × 4k CCD camera. Tilt series for tomography were collected with SerialEM. Tomogram reconstructions were performed in IMOD. Go, Golgi.