Thin section electron micrographs ofnpa2/sec13andnpa1/sec23mutants. Cells growing in early log phase were shifted to the permissive (B and E) or the non-permissive (A, C, D and F) temperature for 4 hours before processing for TEM. Arrowheads denote NPC structures. The arrows in E show multiple layers of NE. Bar equals 1 μm.