Fig. 1.

Arabidopsis female gametophyte and early endosperm development. Processes and events of Arabidopsis FG maturation, endosperm initiation, and early development. A Following FG cellularization, the two PN are sequestered to the CC and migrate towards the egg cell. Upon meeting the PN fuse to generate the SN positioned adjacent to the egg cell nuclei. PN fusion is the final event of FG development after which the SN is mitotically arrested until fertilisation. B Fertilization. Pollen tube penetration of the receptive synergid triggers cell death. Rupture releases the sperm cells which individually fuse with egg and CC. In the CC, nuclear proliferation begins rapidly after fertilization. Antipodal cell degeneration begins at this stage along with cytoplasmic fusion of the persistent synergid with CC. C Endosperm development. Rapid acytokinetic mitosis in the CC occurs accompanied by nuclear migration from the mycropylar to chalazal pole. CC and vacuole enlarge rapidly resulting in nuclei distributed around the periphery of the CC. Cellularization occurs with ongoing mitosis progressing from the CC periphery towards the centre until complete. Key process occurring during each stage are listed in diagrams below. PN polar nuclei, SN secondary nucleus, S synergid cell, rS receptive synergid, pS persistent synergid, E egg cell, A antipodal cells, CC central cell, FG female gametophyte