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In flowering plants the megasporangium is also called the nucellus, and the female gametophyte is sometimes called the embryo sac or embryonic sac. Developmental processes [ edit ]
Megagametogenesis is the process of maturation of the female gametophyte, or megagametophyte, in plants. [1] During the process of megagametogenesis, the megaspore, which arises from megasporogenesis, develops into the embryonic sac, in which the female gamete is housed. [2]
Plant embryonic development, also plant embryogenesis, is a process that occurs after the fertilization of an ovule to produce a fully developed plant embryo. This is a pertinent stage in the plant life cycle that is followed by dormancy and germination . [ 1 ]
The female gametophyte — specifically termed a megagametophyte — is also called the embryo sac in angiosperms. The megagametophyte produces an egg cell for the purpose of fertilization. The ovule is a small structure present in the ovary. It is attached to the placenta by a stalk called a funicle. The funicle provides nourishment to the ovule.
Therefore, the resulting embryo sac is a seven-celled structure consisting of one central cell, one egg cell, two synergid cells, and three antipodal cells. [ 2 ] [ 3 ] The bisporic and tetrasporic patterns undergo varying processes and result in varying embryo sacs as well.
An endosperm is formed after the two sperm nuclei inside a pollen grain reach the interior of a female gametophyte or megagametophyte, also called the embryonic sac.One sperm nucleus fertilizes the egg cell, forming a zygote, while the other sperm nucleus usually fuses with the binucleate central cell, forming a primary endosperm cell (its nucleus is often called the triple fusion nucleus).
Angiosperms have distinctive reproductive organs called flowers, with carpels, and the female gametophyte is greatly reduced to a female embryo sac, with as few as eight cells. Each pollen grains contains a greatly reduced male gametophyte consisting of three or four cells.
Somatic embryogenesis is an artificial process in which a plant or embryo is derived from a single somatic cell. [1] Somatic embryos are formed from plant cells that are not normally involved in the development of embryos, i.e. ordinary plant tissue. No endosperm or seed coat is formed around a somatic embryo.