oogonium

Japanese: oogonium

…they produce eggs inside and are involved in sexual reproduction. In general algae, the female gametophore is called the oogonium, which consists of a single cell in which eggs are produced. In Charophytes, the archegonia is elliptical, with several elongated cells wound around the egg cell in a spiral shape. …

From 【Eggs】

…In algae and fungi, it is a unicellular female gametosac. In mosses and vascular plants, it is formed in the oogonium, at the base of the multicellular archegonium. In angiosperms, which lack the archegonia, one of the eight cells that make up the embryo sac becomes an egg, and it is located at the orifice of the embryo sac along with a synergid cell. Eggs are produced from oocytes by somatic cell division, but in diplomorphic plants such as the seaweed, they are produced through meiosis. …

From [Ovary]

…In vertebrates, the gonad primordium is made up of an epithelium and a medulla surrounded by it. The medulla degenerates, and the ovaries are constructed from the epithelium. The epithelium is called the germinal epithelium, and contains the oogonium (called oogonia in medicine) and oocytes. In amphibians and fish, after the connective tissue that makes up the medulla degenerates, it becomes the ovarian cavity, where mature oocytes, or eggs, are released. …

*Some of the terminology that mentions "oogonium" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…中に卵をつくり有性生殖にかかわる。一般の藻類では雌性配偶子囊は生卵器（せいらんき）oogoniumと呼ばれ，1個の細胞からなりその中に卵がつくられる。車軸藻類では，造卵器は楕円形で，卵細胞のまわりを数本の細長い細胞がらせん状に巻きついたように並んでいる。…

【卵】より

…藻類や菌類では単細胞性の雌性配偶子囊である。生卵器oogoniumの中に，コケ植物や維管束植物では多細胞性の造卵器archegoniumの底部につくられるが，造卵器を欠く被子植物では，胚囊embryo sacをつくるふつう8細胞のうちの一つが卵になり，助細胞を伴って胚囊の珠口側に位置する。卵は卵母細胞から体細胞分裂によってできるが，カサノリなどのように複相の植物体の場合は，減数分裂を経てできる。…

【卵巣】より

…脊椎動物では上皮と，それに包まれた髄質部から成る生殖腺原基の，髄質部分が退化して，上皮部分から卵巣が構築されている。上皮は生殖上皮と呼ばれ，卵原細胞oogonium(医学では卵祖細胞と呼ぶ)，卵母細胞oocyteなどを含む。両生類や魚類では髄質部を成す結合組織が退化した後は卵巣腔となり，成熟した卵母細胞，または卵は，ここに排卵される。…

※「oogonium」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典第２版について | 情報

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