Endocrinology of a Viviparous Amphibian

除环口动物和鸟类外，所有种类的脊椎动物都有生育幼崽的能力。在热带两栖动物的一种独特的目中，蛭形两栖动物，大多数物种都生育幼崽，但控制这一过程的生理机制尚不清楚。有观点认为，胎儿的鳃具有内分泌器官的功能，可以产生类似于哺乳动物胎盘的激素。这种结构在非哺乳动物中尚未被描述。该项目的目的是确定胎儿盲肠组织是否产生类固醇激素。使用的方法包括鉴定体外组织产生的类固醇代谢物和定位已知在类固醇合成中起作用的酶。母体类固醇激素水平将被确定。这些研究将为这一目两栖动物的类固醇内分泌学和活胎控制提供初步的信息。因此，它们将大大有助于了解生殖生物学和这些独特动物的保护，以及其他脊椎动物怀孕的激素控制。

The ability to give birth to live young occurs in all classes ofvertebrates except cyclostomes and birds. In a unique order of tropicalamphibians, the caecilian amphibians, the majority of species give birth tolive young but the physiological mechanisms which control this process areunknown. It is proposed that fetal caecilian gills function as endocrineorgans and produce hormones similar to those produced by mammalianplacentas. Such structures have not been described in non-mammals. Thegoal of this project is to determine whether fetal caecilian tissuesproduce steroid hormones. The methods to be used include identification ofsteroid metabolites produced by tissues in vitro and localization ofenzymes known to function in steroid synthesis. Maternal steroid hormonelevels will be determined.These studies will provide the first information on steroid endocrinologyand the control of live- bearing for this order of amphibians. They willthus contribute substantially to understanding of reproductive biology andconservation of these unique animals and also to hormonal control ofpregnancy in other vertebrates.