Figure 4.

Abnormalities in prefertilized and postfertilized ovules of Athemn1 mutants of Arabidopsis. A, Ovule from a wild-type plant at anthesis showing a fully differentiated embryo sac at the FG7 stage. B, An Athemn1-1 mutant ovule at a comparable stage showing unfused polar nuclei in the center and nondegenerated antipodals at the chalazal end. C, An Athemn1-2 mutant ovule at a comparable stage showing unfused polar nuclei at the center and nondegenerated antipodals at the chalazal end. D, An Athemn1-1 mutant ovule after complementation with the cDNA of the AtHEMN1 gene showing a large fused polar nucleus. E, Postfertilized ovule of a wild-type plant showing a preglobular stage embryo and proliferating endosperm nuclei. F and G, Postfertilized ovules from the Athemn1-1 mutant at a comparable stage to the wild type showing an abnormal preglobular stage embryo and poorly proliferating endosperm nuclei. H, Aborted seed in a mature silique from an Athemn1-1 mutant showing an embryo arrested at the globular stage (the degenerated globular embryo is marked with dotted lines). APC, Antipodal cell; CC, central cell; E, embryo; EC, egg cell; ESN, endosperm nucleus; SC, synergid cell; UPN, unfused polar nuclei.