Dual axis electron tomography of the TGN and DMS reveals fusion of vesicles with the pre-DMS. (A) TEM image of the Golgi complexes oriented so that the trans-sites (TGN) lie facing the pre-DMS. Some vesicles are in close apposition to the pre-DMS (arrowheads). Bar, 500 nm. (B-C) Selected tomographic sections showing fusion of TGN-derived vesicles with the pre-DMS. A higher magnification of the boxed area in B is shown in C, and the arrowhead points to the zone of continuity between the membranes of the vesicle and the pre-DMS. (D-E) Alignment of larger vesicles along the pre-DMS. Fusion of a vesicle with the pre-DMS (arrowhead in D). g, Golgi stacks; n, nucleus.