Several hormones regulate anuran larval development, most notably thyroid hormones (THs). In anurans, metamorphosis fails when the thyroid gland is absent or inactivated, resulting in giant tadpoles. Larval gigantism occurs naturally in neotropical frogs of the genus Pseudis as a result of a prolonged larval period. Its thyroid function is poorly investigated and the focus of this study. We describe qualitative and quantitative variations in larval development for field‐captured specimens of Pseudis platensis and compare those to the development of two sympatric species, Phyllomedusa sauvagii and Pithecopus azureus, which have small tadpoles and a shorter larval period. We describe morphological changes in the thyroid glands of larval and adult specimens. In contrast to other species with similar ecological requirements, P. platensis exhibits distinct glandular activity. During premetamorphosis, there was little or no thyroid activity, a period in which the tadpole reached 70% of its maximum size. Development and degree of activity of the thyroid gland determine the duration of the early stages of the larval period. Thyroid gland histology in tadpoles appears to correlate with the TH activity, and in turn with the diversity in anuran life history transitions.

中文翻译：

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Pseudis platensis（Anura，Hylidae）幼虫发育过程中甲状腺的组织学和显微解剖学

几种激素调节无尾幼虫的发育，最显着的是甲状腺激素 (THs)。在无尾类中，当甲状腺缺失或失活时，变态失败，导致巨大的蝌蚪。由于幼虫期延长，幼虫巨人症自然发生在 Pseudis 属的新热带蛙类中。其甲状腺功能研究不足，也是本研究的重点。我们描述了野外捕获的 Pseudis platensis 标本的幼虫发育的定性和定量变化，并将这些变化与两个同域物种 Phyllomedusa sauvagii 和 Pithecopus azureus 的发育进行了比较，它们具有较小的蝌蚪和较短的幼虫期。我们描述了幼虫和成虫标本甲状腺的形态变化。与具有相似生态要求的其他物种相比，P. platensis 表现出独特的腺体活动。在变态前，几乎没有或没有甲状腺活动，在此期间蝌蚪达到其最大尺寸的 70%。甲状腺的发育和活动程度决定了幼虫早期阶段的持续时间。蝌蚪的甲状腺组织学似乎与 TH 活动相关，进而与无尾目生活史转变的多样性相关。