embryo sac


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Related to embryo sac: pollen grain, double fertilization, synergid

embryo sac

n.
The female gametophyte of a seed plant, within which the embryo develops.
Embryo sacclick for a larger image
Fig. 147 Embryo sac . Vertical section.

embryo sac

the female GAMETOPHYTE of flowering plants, consisting of a sac-like structure inside the OVULE in which are found six HAPLOID cells (without cell walls) and two haploid nuclei. See Fig. 147 . All cells have originated from one haploid nucleus and so are all genetically identical. The name ‘embryo sac’ comes from the fact that the plant embryo develops from within the sac. Two MALE GAMETE NUCLEI enter the embryo sac from the POLLEN TUBE and carry out a ‘double’ fertilization. One male nucleus fuses with the egg cell to give a DIPLOID zygote (the future plant), the other male nucleus fuses with two polar nuclei giving a triploid fusion nucleus (3n) which develops into the ENDOSPERM (the future food supply in some species).
References in periodicals archive ?
May 17 ~ May 18###Two-celled pollen###Binuclear or four nuclear embryo sac
Instead, we found that double fertilization did not happen in chrysanthemum embryo sacs, as the embryo sacs were degenerating and the degradation residues of synergids, egg cells, or central nuclei could be easily observed in the embryo sacs (Figures 2(a) and 2(b)).
However, and as a difference with recent reviews, I will pay special attention in this review to the other two, less known alternatives: male-derived haploid embryogenesis within the embryo sac, and meiocyte-derived callogenesis.
Year-to-year variation in the developmental stage of the embryo sac at anthesis in flowers of apricot (Prunus armeniaca L.).
They confirmed their hypothesis after varying auxin concentrations in the embryo sac of the plant.
In one aspect of this work, the scientists are investigating how such messages may help the growing pollen tube find its way to the embryo sac.
Two polar nuclei met in the middle of the embryo sac and fused to form a single large central cell before fertilization (Fig.
Even though the extra fertilized egg later dies off -- and the nonflowering Ephedra's embryo ultimately feeds on its embryo sac cells -- Friedman says this is evidence of how endosperm once formed.
The functional megaspore develops into an embryo sac, which gives rise to a Polygonum type.
A total of 472 ovaries, fixed at monthly intervals throughout a complete flowering season, showed over 76% of the mature ovules bearing one meiotic embryo sac. The remaining ovules had immature or aborted embryo sacs, but aposporous sacs were not observed.
Since the archespore ultimately gives rise to the megagametophyte (embryo sac), the nucellus is the part of the sporophyte that encloses the megagametophyte, separating it from the inner integument, although some of the nucellus may have degenerated at floral anthesis.
Mitotic divisions take placed in the functional megaspore and resulted to form a two nucleated embryo sac (Fig.