PM asymmetries during cell fusion. (A) Table classifying the set of tomograms from h90 WT cells used in this study, according to PM morphology along the four stages of fusion. (B–D) Virtual z-slices through tomograms of mating cells showing PM asymmetries (convex versus concave) in close CW contact stage (B), PM contact stage (C), and post-fusion stage (D). Blue arrows point to fusion pores; yellow arrows point to unresolved regions at the PM. Scale bars, 100 nm.