Fig. 9

Tomographic models illustrating the variability in size and geometry of C1 cis-Golgi cisterna initials. The cisternae are color coded: C1 (orange), C2 (green), C3 (blue), C4 (pink), C5 (yellow), C6 (purple), C7 (red). The smallest C1 cisterna initial seen in a has a surface area equivalent to 3–4 COPII vesicles. The larger cisterna initials (a–c) possess branched, tubular architectures with many tubules exhibiting COPII vesicle-size spherical ends. The Golgi stacks depicted in a and b are shown in face-on views, and in c the stack is presented at an angle to highlight both the geometry of the C1 cisterna and the spatial organization of the stack. Bars 0.1 µm