Female gametophyte development in yao/+ siliques. Confocal micrographs showing a female gametophyte at four-nucleate stage (FG4) (A) and FG5 stages (B) from wild-type plants, female gametophytes (C-E) from the same yao/+ pistil arrested at FG4 with misplaced nuclei at the micropylar pole (C, D) and reached to the FG5 stage (E). Compare the positioning of nuclei in A and C-D. PN, polar nucleus; EN, egg nucleus; SN, synergid nucleus; V, vacuole. Arrows indicating nucleus of the female gametophyte. Bar = 20 μm.