AskDefine | Define embryo

Dictionary Definition

embryo

Noun

1 (botany) a minute rudimentary plant contained within a seed or an archegonium
2 an animal organism in the early stages of growth and differentiation that in higher forms merge into fetal stages but in lower forms terminate in commencement of larval life [syn: conceptus, fertilized egg]

User Contributed Dictionary

English

Noun

  1. An unborn baby that is less developed than a foetus.
  2. An organism in the earlier stages of development before it emerges from the egg, or before metamorphosis.
  3. In viviparous animals, the young animal's earliest stages in the mother's body
  4. In humans, usually the cell growth up to the end of the seventh week in the mother's body
  5. A rudimentary plant contained in the seed.
  6. The beginning; the first stage of anything.

Derived terms

Related terms

Translations

an unborn baby that is less developed than a foetus
  • French: embryon
  • Hebrew: עובר
an organism in the earlier stages of development before it emerges from the egg, or before metamorphosis
in viviparous animals: the young animal's earliest stages in the mother's body
in humans: the cell growth up to the end of the seventh week in the mother's body
botany: a rudimentary plant contained in the seed
the beginning; the first stage of anything

Extensive Definition

An embryo (from Greek: , plural , lit. "that which grows," from en- "in" + bryein "to swell, be full") is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination. In humans, it is called an embryo from the moment of fertilisation until the end of the 8th week, whereafter it is instead called a fetus.

Development

The development of the embryo is called embryogenesis. In organisms that reproduce sexually, once a sperm fertilizes an egg cell, the result is a cell called the zygote that has all the DNA of two parents. The resulting embryo derives 50 percent of its genetic makeup from each parent. In plants, animals, and some protists, the zygote will begin to divide by mitosis to produce a multicellular organism. The result of this process is an embryo.

In animals

In animals, the development of the zygote into an embryo proceeds through specific recognizable stages of blastula, gastrula, and organogenesis. The blastula stage typically features a fluid-filled cavity, the blastocoel, surrounded by a sphere or sheet of cells, also called blastomeres.
  • Plants: In botany, a seed plant embryo is part of a seed, consisting of precursor tissues for the leaves, stem (see hypocotyl), and root (see radicle), as well as one or more cotyledons. Once the embryo begins to germinate — grow out from the seed — it is called a seedling. Plants that do not produce seeds, but do produce an embryo, include the bryophytes and ferns. In these plants, the embryo is a young plant that grows attached to a parental gametophyte.
  • Animals: The embryo of a placental mammal is defined as the organism between the first division of the zygote (a fertilized ovum) until it becomes a fetus. In humans, the embryo is defined as the product of conception from implantation in the uterus through the eighth week of development. An embryo is called a fetus at a more advanced stage of development and up until birth or hatching. In humans, this is from the eighth week of gestation.
embryo in Arabic: جنين
embryo in Catalan: Embrió
embryo in Czech: Embryo
embryo in Danish: Embryon
embryo in German: Embryo
embryo in Estonian: Embrüo
embryo in Spanish: Embrión
embryo in Esperanto: Embrio
embryo in Persian: جنین
embryo in French: Embryon
embryo in Galician: Embrión
embryo in Ido: Embriono
embryo in Indonesian: Embrio
embryo in Italian: Embrione
embryo in Luxembourgish: Embryo
embryo in Lithuanian: Gemalas
embryo in Dutch: Embryo
embryo in Japanese: 胚
embryo in Norwegian: Embryo
embryo in Occitan (post 1500): Embrion
embryo in Polish: Embrion
embryo in Portuguese: Embrião
embryo in Russian: Эмбрион
embryo in Simple English: Embryo
embryo in Slovak: Embryo
embryo in Slovenian: Zarodek
embryo in Serbo-Croatian: Zametak
embryo in Serbian: Ембрион
embryo in Finnish: Alkio
embryo in Swedish: Embryo
embryo in Turkish: Embriyo
embryo in Ukrainian: Ембріон
embryo in Urdu: جنین
embryo in Chinese: 胚胎
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