embryo sac


noun Botany.

the megaspore of a seed-bearing plant, situated within the ovule, giving rise to the endosperm and forming the egg cell or nucleus from which the embryo plant develops after fertilization.

Origin of embryo sac

First recorded in 1870–75

Example sentences from the Web for embryo sac

British Dictionary definitions for embryo sac

embryo sac

noun

the structure within a plant ovule that contains the egg cell: develops from the megaspore and contains the embryo plant and endosperm after fertilization

Scientific definitions for embryo sac

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. See more at gametophyte pollination.