Primary follicle

…Oocytes remain dormant in the ovaries in the prophase stage until they reach maturity, at least a dozen years after puberty, and in some cases for as long as 40 years. Immature oocytes are individually surrounded by flattened follicular epithelial cells and are called primary follicles (or primordial follicles). In newborns, both ovaries are filled with approximately 400,000 primary follicles, but this number decreases significantly due to follicular atresia, as described below. …

*Some of the terminology that refers to "primary follicles" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…卵母細胞は思春期以後，順次成熟するまで，少なくも十数年，長いものは40年も，分裂前期の段階のまま卵巣の中にひそんでいる。未発達の段階の卵母細胞は1個ずつ扁平な卵胞上皮細胞に包まれ，一次卵胞(または原始卵胞)とよばれる。新生児では両側の卵巣に約40万個の一次卵胞(濾胞)が充満しているが，後述の卵胞閉鎖によって著しく減少する。…

※「一次卵胞」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