Embryo Sac Development

Female gametophyte development begins with the post-meiotic degeneration of three of the daughter cells, leaving only one functional gametophyte. This single-nucleate (FG1) gametophyte undergoes nuclear division without cell division to give rise to the double-nucleate FG2 stage. The nuclei migrate to the opposite ends of the embryo sac syncytium and a large vacuole forms between them, defining the FG3 stage. Two more rounds of nuclear division (stage FG4) are followed by cellularization (stage FG5). Fusion of the two polar nuclei leads to the seven-nucleate, seven-celled embryo sac (stage FG6) containing an egg cell, two synergids, a central cell and three antipodals. Degeneration of the three antipodals yields the final four-celled embryo sac (stage FG7), ready for fertilization. (Stages as described by Christensen et al. 1997)

Follow the links to see images of wild type embryo sac development using two different microscopy methods - staining with propidium iodide followed by confocal microscopy or embedding and sectioning and staining with toluidine blue. I took these images while a graduate student in the lab of Sebastian Bednarek in the Department of Biochemistry at the University of Wisconsin, Madison, while studying a mutant (dynamin related protein 2) with defective embryo sac developement and pollen development.