ENVIRONMENTAL SEX DETERMINATION AND DIFFERENTIATION

哺乳动物、鸟类和爬行动物构成了脊椎动物。 在所有 哺乳动物和鸟类，以及许多爬行动物，性别是在受精时决定的。 基因型性别决定（genotypic sex determination，GSD）在某些爬行动物中， 然而，蛋孵化的温度决定了 胚胎孵化为男性或女性（温度依赖性性别 因此，在这些物种中，胚胎最初是 双电位，只有后来才向男性或女性通道化 表型发生。最初的双能性和后来的性别决定 通过物种展示TSD提供了一个独特的模式系统的研究， 性别决定和性别分化的机制在所有的灵长类动物 脊椎动物，包括人类。 我们最近发现，给胚胎注射雌激素 在产生雄性的温度下孵育引起卵巢发育， 覆盖任何温度效应。拟议的研究将调查 (i)这种雌激素效应是如何发生的，（ii）在正常情况下， 类固醇激素是在性腺致力于 睾丸/卵巢发育，以及（iii）胚胎类固醇是否具有 与哺乳动物在非性腺表型分化中的作用相似 还有鸟类我们还发现胚胎发育的温度 经验深刻地影响其成年形态，生理， 行为孵化温度组织成虫的机制 性行为将通过对胚胎的荷尔蒙控制来研究， 通过阉割和/或给予合成类固醇激素的新生儿 激素激动剂和拮抗剂、酶抑制剂和类固醇抗血清。 总之，这些实验将确定GSD和TSD在多大程度上 在控制性腺方面具有相似的生理或生化基础 决定和性别分化的生物心理学。 拟议的研究对理解、 脊椎动物的性发育，包括 不同程度的性行为研究将使用 多种技术，包括行为测试，组织学， - 免疫细胞化学，激素受体的单克隆抗体， 合成类固醇激动剂和拮抗剂，高性能液体 色谱法、气相色谱/质谱法。光谱法，和 放射免疫法

Mammals, birds, and reptiles constitute the amniote vertebrates. In all mammals and birds, and in many reptiles, sex is determined at fertilization by genotype (genotypic sex determination or GSD). In some reptiles, however, the temperature at which the egg incubates determines whether the embryo hatches as a male or a female (temperature-dependent sex determination or TSD) Thus, in these species, embryos are initially bipotential and only later does channelization toward the male or female phenotype occur. The initial bipotentiality and later determination of sex by species exhibiting TSD offer a unique model system for studies of the mechanisms of sex determination and sexual differentiation in all amniote vertebrates, including man. We have discovered recently that the administration of estrogen to embryos incubating at male-producing temperatures causes ovarian development, over-riding any temperature effect. The proposed research will investigate (i) how this estrogen effect occurs, (ii) whether, under normal conditions, steroid hormones are present before the gonad is committed to testicular/ovarian development, and (iii) whether embryonic steroids have a similar role in the differentiation of non-gonadal phenotypes as in mammals and birds. We also have discovered that the temperature that an embryo experiences profoundly affects its adult morphology, physiology, and behavior. The mechanisms by which incubation temperature organizes adult sexuality will be studied through hormonal manipulations of embryos and neonates by castration and/or administration of steroid hormones, synthetic hormone agonists and antagonists, enzyme inhibitors, and steroid antisera. Together, these experiments will determine the extent to which GSD and TSD have similar physiological or biochemical bases in the control of gonad determination and in the biopsychology of sexual differentiation. The proposed studies are of fundamental importance to understanding, the development of sexuality in vertebrates, including the relation of different levels of sexuality within an individual. The studies will use multiple techniques, including behavioral testing, histology, -immunocytochemistry, monoclonal antibodies for hormone receptors, synthetic steroid agonists and antagonists, high-performance liquid chromatography, gas chromatography/mass. spectrometry, and radioimmunoassay.