Hayes T B, Menendez K P
Group in Endocrinology, Museum of Vertebrate Zoology, Berkeley, California 94720-3140, USA.
Gen Comp Endocrinol. 1999 Aug;115(2):188-99. doi: 10.1006/gcen.1999.7321.
The current study examined the role of steroids in primary and secondary sex differentiation in the African reedfrog (Hyperolius argus: Hyperolidae). This species is sexually dimorphic: males have a solid green dorsum and females are reddish-brown with large white spots. This study is the first to report the effects of sex steroids on the development of a sexually dichromatic species and the first to examine the role of sex steroids on development of the vocal sac. Both males and females metamorphosed solid green without spots. Approximately 2 months after metamorphosis, control females transformed to the female-typical color pattern. Control males never developed this color pattern (remained green), but developed vocal sacs. To examine the role of sex steroid hormones on primary (gonadal differentiation) and secondary (vocal sac development and dorsal coloration) sex differentiation, testosterone (T) or estradiol-17beta (E(2)) were administered throughout larval development. At metamorphosis, 53% of the controls were males, based on gross gonadal morphology and histology of a subsample. Both doses of T produced 100% males. All E(2)-treated animals had ovarian cavities and/or follicles when examined histologically (at both doses) but 50% had testicular tissue in addition to these ovarian characteristics. Both doses of T induced vocal sac development and both doses of E(2) induced female coloration. Thus, both T and E(2) induced secondary sex characteristics (vocal sac development and dorsal color change, respectively) but E(2) produced hermaphroditic gonads, whereas T induced complete sex reversal.
本研究考察了类固醇在非洲芦苇蛙（Hyperolius argus：树蛙科）初级和次级性别分化中的作用。该物种具有两性异形：雄性背部为纯绿色，雌性为红棕色且带有大的白色斑点。本研究首次报道了性类固醇对具有两性异色物种发育的影响，也是首次考察性类固醇在声囊发育中的作用。雄性和雌性幼蛙变态后均为无斑点的纯绿色。变态后约2个月，对照雌性转变为典型的雌性体色模式。对照雄性从未发育出这种体色模式（仍为绿色），但发育出了声囊。为了研究性类固醇激素在初级（性腺分化）和次级（声囊发育和背部着色）性别分化中的作用，在整个幼体发育过程中给予睾酮（T）或雌二醇-17β（E₂）。变态时，根据大体性腺形态和部分样本的组织学检查，53%的对照为雄性。两种剂量的T均产生了100%的雄性。经组织学检查（两种剂量），所有经E₂处理的动物都有卵巢腔和/或卵泡，但其中50%除了这些卵巢特征外还具有睾丸组织。两种剂量的T均诱导了声囊发育，两种剂量的E₂均诱导了雌性体色。因此，T和E₂均诱导了次级性征（分别为声囊发育和背部颜色变化），但E₂产生了雌雄同体的性腺，而T诱导了完全性逆转。
