(c) The female gametophyte or embryo sac is located inside the nucellus, enclosed within the integuments. In a majority of flowering plants, one of the megaspore is functional while the other three degenerate. Three repeated mitotic divisions of the functional megaspore result in the formation of seven-celled or eight-nucleate embryo sac.
Six of the eight nuclei are organised at the two poles. Three cells grouped at micropylar end forms egg-apparatus and 3 at the chalazal end forms antipodal cells. The large
central cell at the center has two polar nuclei. The meiotic divisions in the formation of embryo sac are strictly free nuclear, that is nuclear divisions are nat followed immediately by celi-wall formation. Gametophytes situated at micropylar end, not at chalazal end.