Bot. the female gametophyte of a flowering plant, consisting typically of a microscopic elongated sac that is situated within the ovule and contains eight nuclei in seven cells: it gives rise to the embryo and endosperm of the seed after fertilization
Embryo sac. (n.d.). In YourDictionary. Retrieved from https://www.yourdictionary.com/embryo-sac
An oval structure within an ovule of an angiosperm that contains the egg. Together with the fertilized egg, it develops into a seed. The embryo sac is the female gametophyte of angiosperms, consisting of eight nuclei: the egg and two adjacent and short-lived synergids that are near the micropyle (the opening where the pollen nuclei will enter),
two central nuclei (which will combine with one of the pollen nuclei to form the endosperm),
and three antipodal nuclei at the end of the embryo sac opposite the micropyle. Like the synergids, these nuclei degenerate at or shortly after fertilization.
It may be wholly absorbed by the progressive growth of the embryo within the embryo-sac, or it may persist as a definite and more or less conspicuous constituent of the seed.
Ultimately the apex of the tube comes in contact with the tip of the embryo-sac and perforates it.
Ek, Nucleus of embryo-sac. ei, Egg-apparatus.
A pro-embryo - a cellular row of which the cell nearest the micropyle becomes attached to the apex of the embryo-sac, and thus fixes the position of the developing embryo, while the terminal cell is projected into its cavity.
- Vertical section of the ovule of the Austrian Pine (Pinus austriaca), showing the nucellus a, consisting of delicate cellular tissue containing deep in its substance an embryo-sac b.