embryo sac

American  

noun

Botany.

1. 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.

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embryo sac British  

noun

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

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embryo sac Scientific  

1. 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.

2. See more at gametophyte pollination

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Etymology

Origin of embryo sac

First recorded in 1870–75

Example Sentences

Together, these cells are called the megagametophyte, or embryo sac.

From Textbooks • Jan. 1, 2015

Two polar nuclei are inside the central cell in the middle of the embryo sac.

From Textbooks • Jan. 1, 2015

The mature embryo sac contains one egg cell, two synergids or “helper” cells, three antipodal cells, and two polar nuclei in a central cell.

From Textbooks • Jan. 1, 2015

The two sperm cells are deposited in the embryo sac.

From Textbooks • Apr. 25, 2013

M, embryo sac of a full-grown ovule, × 150.

From Elements of Structural and Systematic Botany For High Schools and Elementary College Courses by Campbell, Douglas Houghton