Endocrinology of a Viviparous Amphibian

除了环口动物和鸟类外，所有种类的脊椎动物都有产下活幼崽的能力。在热带两栖动物中，盲肠两栖动物是一个独特的目，大多数物种都会生下幼崽，但控制这一过程的生理机制尚不清楚。有人认为，胎儿盲肠的鳃起着内分泌器官的作用，并产生与哺乳动物胎盘类似的激素。这种结构在非哺乳动物中还没有被描述过。该项目的目标是确定胎儿盲肠组织是否会产生类固醇激素。使用的方法包括鉴定体外组织产生的类固醇代谢物，以及已知在类固醇合成中起作用的酶的定位。将测定母体类固醇激素水平。这些研究将提供有关类固醇内分泌学和该目两栖动物活产控制的第一批信息。因此，它们将对了解生殖生物学和保护这些独特的动物以及其他脊椎动物怀孕的荷尔蒙控制做出重大贡献。

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.