Ontogeny of Immunity in Frogs/Effects of Metamorphosis

南非蝌蚪的免疫反应模式 爪蛙，非洲爪蟾，与成年蛙不同。 变形是一个过渡时期，分离的两个 模式. 本研究的目的是检查 假设成人免疫系统的发展需要 变态，其特点是失去了一个主要的 幼虫淋巴细胞的数量和新的成年淋巴细胞的替代， 型淋巴细胞。 为了证明或反驳这一假设，幼虫 胸腺或脾细胞群将在细胞遗传学上 他们的命运，以及他们在蜕变后的命运， 跟踪了 通过将三倍体胸腺或脾脏植入二倍体 在他们中的一些主机和阻止变态，这将是 确定T和B细胞群的更新是否在 变态依赖于甲状腺激素。 因为 变态是由甲状腺激素调节的， 受皮质类固醇激素的调节， 甲状腺激素和皮质类固醇激素在促进 免疫系统中的变态依赖性变化将是 分析了 这些研究将有助于更好地了解 两栖动物免疫系统的个体发育， 在个体发育过程中调节淋巴细胞的产生， 免疫系统发育的神经内分泌调节， 以及对“自我”的免疫耐受性是如何发展的。

The immune response pattern of tadpoles of the South African clawed frog, Xenopus laevis, is distinct from that of the adult. Metamorphosis is a transitional period that separates the two patterns. The objectives of this research are to examine the hypothesis that development of the adult immune system requires metamorphosis and is characterized by the loss of a major population of larval lymphocytes and replacement with new, adult- type lymphocytes. To prove or disprove the hypothesis, larval thymus or spleen cell populations will be cytogenetically labelled, and their fate during and after metamorphosis will be followed. By implanting triploid thymus or spleen into diploid hosts and blocking metamorphosis in some of them, it will be determined whether renewal of T and B cell populations at metamorphosis is dependent on thyroid hormones. Because metamorphosis is regulated by thyroid hormones whose effects may be modulated by corticosteroid hormones, the direct effects of thyroid hormones and corticosteroid hormones in promoting metamorphosis-dependent changes in the immune system will be analyzed. These studies will contribute to a better understanding of the ontogeny of the immune system of amphibians, the mechanisms that regulate production of lymphocytes during ontogeny, the neuroendocrine regulation of development of the immune system, and how immunological tolerance to "self" develops.