Adenohypophysial-thyroid activity of the tiger salamander, Ambystoma tigrinum, as a function of metamorphosis and captivity.
Adenohypophysial-thyroid activity of the tiger salamander, Ambystoma tigrinum, as a function of metamorphosis and captivity.
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虎蝾螈（Ambystoma tigrinum）的腺垂体甲状腺活性作为变态和圈养的函数。
DOI：
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发表时间：
1987
期刊：
影响因子：
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通讯作者：
D. O. Norris
中科院分区：
文献类型：
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作者：
M. Norman;J. A. Carr;D. O. Norris
本研究的目的是确定时间的腺垂体激活在变态的虎蝾螈，虎钝口螈。它由两部分组成：1）测定血浆甲状腺激素浓度并分析甲状腺组织学作为变态阶段的函数，2）分析变态期间甲状腺摄取125 I的时间过程作为内源性促甲状腺激素（TSH）水平的指标。三碘甲状腺原氨酸（T3）和甲状腺素（T4）的显着增加，首先是明显的变质高潮（第二阶段）的发病。两种激素的最高水平没有观察到，但是，直到完成鳃吸收（第七阶段）。未观察到与变性转化明确相关的甲状腺组织学变化。甲状腺积累125I在一个缓慢的，但线性的方式在premetamorphic幼虫（阶段I）。然而，摄取表现出快速高峰期早期（第二阶段），在最大浓度的甲状腺激素被观察到。此外，摄取保持在第七阶段的变质前水平以上，结合T4和T3的最高水平。单独圈养产生了一个小的，但显着增加血浆中的T3浓度。它对甲状腺组织学或125I摄取均无显著影响。这些结果表明，腺垂体激活发生迅速，是最大的变态高潮的开始。
The aim of this study was to determine the timing of adenohypophysial activation during metamorphosis of the tiger salamander, Ambystoma tigrinum. It consisted of two parts: 1) determination of plasma thyroid hormone concentrations and analysis of thyroid gland histology as a function of metamorphic stage and 2) analysis of the time-course of uptake of 125I by the thyroids during metamorphosis as an indicator of endogenous thyrotropin (TSH) levels. Significant increases in both triiodothyronine (T3) and thyroxine (T4) first were evident at the onset of metamorphic climax (stage II). Maximum levels of both hormones were not observed, however, until the completion of gill resorption (stage VII). No changes in thyroid histology were observed that could be unambiguously related to metamorphic transformation. The thyroids accumulated 125I in a slow but linear fashion in premetamorphic larvae (stage I). However, uptake exhibited a rapid peak during early climax (stage II), before maximum concentrations of thyroid hormones were observed. In addition, uptake was maintained above premetamorphic levels at stage VII, in conjunction with maximum levels of T4 and T3. Captivity alone produced a small but significant increase in plasma concentrations of T3. It produced no significant effect on either thyroid histology or uptake of 125I. These results indicate that adenohypophysial activation occurs rapidly and is maximal at the onset of metamorphic climax.