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

See Examples For:

embryo sac

These seven cells are the female gametophyte, known as the embryo sac.

From Textbooks ● Jan. 1, 2018

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

From Textbooks ● Jan. 1, 2015

A double-layered integument protects the megasporangium and, later, the embryo sac.

From Textbooks ● Jan. 1, 2015

During the second phase, megagametogenesis, the surviving haploid megaspore undergoes mitosis to produce an eight-nucleate, seven-cell female gametophyte, also known as the megagametophyte or embryo sac.

From Textbooks ● Jan. 1, 2015

The integuments grow with the embryo sac, and become brown and hard, forming the shell of the seed.

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