Fig. S1 Enlarged micrograph of the Golgi stack in the
lower left corner of Fig. 2 from a different plane of the
tomogram (combination of three tomographic slices). The
Golgi stack comprises two cis (c), two medial (m), and
three trans (t) cisternae and exhibits strong cis-to-trans
polarity regarding luminal width and electron density.
Budding profiles of coat-bearing vesicles are observed at
cis (arrow) and medial cisternae (inset; single
tomographic slice). Secretory vesicles (SV) containing
electron dense material form at the edges of the trans
Golgi network (TGN) cisterna. MV microvesicle. Bars:
100 nm, 50 nm (inset)