• embryo
  • An early stage of development in multicellular organisms.
Abstract from DBPedia
    An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm cell. The resulting fusion of these two cells produces a single-celled zygote that undergoes many cell divisions that produce cells known as blastomeres. The blastomeres are arranged as a solid ball that when reaching a certain size, called a morula, takes in fluid to create a cavity called a blastocoel. The structure is then termed a blastula, or a blastocyst in mammals. The mammalian blastocyst hatches before implantating into the endometrial lining of the womb. Once implanted the embryo will continue its development through the next stages of gastrulation, neurulation, and organogenesis. Gastrulation is the formation of the three germ layers that will form all of the different parts of the body. Neurulation forms the nervous system, and organogenesis is the development of all the various tissues and organs of the body. A newly developing human is typically referred to as an embryo until the ninth week after conception, when it is then referred to as a fetus. In other multicellular organisms, the word "embryo" can be used more broadly to any early developmental or life cycle stage prior to birth or hatching.

    胚(はい、独,英: Embryo)とは、多細胞生物の個体発生におけるごく初期の段階の個体を指す。胚子(はいし)ともいう。一般に、有性生殖を行う生物では、胚発生(英: embryonic development)は受精直後から始まり、組織や器官などの構体(身体の構造)が形成されるまで続くライフサイクルの一部である。各胚は、配偶子の融合(雌の卵細胞と雄の精細胞の融合である受精の過程)から生じた単一細胞の接合子として発生を開始する。胚発生の最初の段階では、単細胞の接合子が、卵割と呼ばれる急速な細胞分裂を何度も繰り返し、細胞が球形に配列したような胞胚を形成する。次に、胞胚期の胚の細胞は、原腸形成(原腸陥入とも)と呼ばれる過程を経て、層状に再配列を始める。これらの層はそれぞれ、神経系、結合組織、器官など、発生中の多細胞生物のさまざまな部分を生み出す。 の場合は通常、受精後9週目までは 胚 と呼ばれ、それ以降は 胎児 と呼ばれる。他の多細胞生物では、胚 という言葉は、誕生や孵化前の初期の発生段階やライフサイクルで広く使われることがある。

    (Source: http://dbpedia.org/resource/Embryo)