• 作者： 許織雲; 王慧珍
• 作者服務機構： 國防醫學院生物形態學系
• 中文摘要： 17β-ureido-1, 4-androstadiene-3-one（17β-ureide類固醇）屬人工合成之類固醇，為助孕素之同功異體。可抑
  制類固醇合成步驟中之17α-羥化?及C17～20連碳分解?，而使雄性素不得合成，後者又為雌性素之先質，故雌雄二素之
  合成均受到阻礙。性類固醇誘導性腺分化學說謂雌雄二素可致使性腺分別發育為卵巢或睪丸。根據此項理論，本實驗乃以
  17β-ureide類固醇處理牛蛙蝌蚪，研究性腺在既無雌性素，又缺雄性素之情況下，如何分化；結果獲知，以該抑制劑浸
  泡蝌蚪，雖經五個月之久，性腺發育正常，但以之注射蝌蚪，則部分卵巢退化為不育性腺，其內含物除少數正常及已壞死
  之卵母細胞外，餘為大量之結締組織；有的不育性腺極小，全部均為結締組織；其餘經注射後之性腺，分化為正常之卵巢
  ，中間性腺及睪丸，此顯示17β-ureide類固醇可能抑制雌雄二素之合成而使卵巢退化為不育性腺。此結果可支持性類固
  醇誘導性腺分化之學說。但此等不育性腺之類固醇合成步驟究竟如何，尚待進一步之探討。y
• 英文摘要： 17β-ureido-1,4-androstadiene-3-one (17β-ureide steroid) is a synthetic progestin analogue. It iscapable of inhibiting 17-α-hydroxylase and C17-20 lyase, resulting in an accumulation of 17α-hydroxy-progesterone and a shortage of androstenedione. The latter is the precursor of testosterone which, inturn, is the forerunner of estrogens. Therefore, 17β-ureide steroid can block synthesis of androgens andestrogens. According to the steroid theory of gonadal sex differentiation, sex hormones are implicated ingonadal development. The present study aims to investigate this problem in gonads of Rana catesbeianatadpoles by treatment of tadpoles with 17β-ureide steroid. When tadpoles were reared in water containingthe inhibitor for five months, gonadal differentiation was normal. However, after IP injection of 17β-ureide steroid into the tadpoles, some ovaries degenerated and became partially sterile, consisting mostlyof connective tissue and some apparently normal and degenerated oocytes. Complete sterile gonads withonly connective tissue but no germ cells were also found. The remaining gonads were, nevertheless, normal;they were ovaries, intersexes and testes. This findings support the steroid theory of gonadal differentiation,indicating that the gonad will become neither an ovary nor a testis when synthesis of both androgens andestrogens is arrested.
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