The increased incidence of human thyroid disorders, particularly in women, suggests that the exposure to endocrine-disrupting compounds (EDCs) together with sex-related factors could play a role in thyroid dysregulation. Since the herbicide atrazine (ATZ) is an environmental EDC suspected to behave as a thyroid disruptor, and Caiman latirostris is a crocodilian species highly sensitive to endocrine disruption that can be exposed to ATZ, this study aimed to describe the histoarchitecture and sexually dimorphic features of the thyroid gland of C. latirostris, and to determine the long-term effects of in ovo exposure to an environmentally relevant dose of ATZ (0.2 ppm) on its thyroid gland and growth. Control caimans showed no sexual dimorphisms. In contrast, ATZ-exposed caimans showed altered embryo growth but an unaltered temporal pattern of development and a sexually dimorphic response in the body condition index growth curves postnatally, which suggests a female-related increase in fat storage. Besides, both male and female exposed caimans showed increases in the size of the thyroid stromal compartment, content of interstitial collagen, and follicular hyperplasia, and decreases in the expression of androgen receptor in the follicular epithelium. ATZ-exposed females, but not males, also showed evidences of thyroid enlargement, colloid depletion, increased follicular epithelial height and increased presence of microfollicular structures. Our results demonstrate that prenatal exposure of caimans to ATZ causes thyroid disruption and that females were more vulnerable to ATZ than males. The effects were organizational and observed long after exposure ended. These findings alert on ATZ side-effects on the growth, metabolism, reproduction and development of non-target exposed organisms, particularly females.

中文翻译：

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卵对环境相关剂量的阿特拉津的长期接触对凯门鳄（Caiman latirostris）甲状腺的长期影响。

人类甲状腺疾病（尤其是女性）的发病率增加表明，暴露于内分泌干扰性化合物（EDC）以及与性相关的因素可能在甲状腺失调中起作用。由于除草剂at去津（ATZ）是一种环境EDC，被怀疑具有甲状腺破坏作用，而凯门鳄（Caiman latirostris）是对内分泌破坏高度敏感的鳄鱼，可暴露于ATZ，因此本研究旨在描述该植物的组织结构和两性特征以确定C. latirostris的甲状腺，并确定与环境相关剂量的ATZ（0.2 ppm）的卵内暴露对其卵腺和生长的长期影响。对照凯门鳄未显示出性别二态性。相反，暴露于ATZ的凯门鳄显示出胚胎的生长发生了变化，但是在出生后的身体状况指数增长曲线中，发育的时间模式没有改变，并且发生了性二态性反应，这表明女性与脂肪的储存有关。此外，雄性和雌性暴露的凯门鳄均表现出甲状腺间质腔的大小增加，间质胶原含量和滤泡增生，并且滤泡上皮中雄激素受体的表达降低。暴露于ATZ的雌性而不是雄性也显示出甲状腺肿大，胶体耗竭，滤泡上皮高度增加和微泡结构增加的迹象。我们的结果表明，凯门鳄在产前暴露于ATZ会引起甲状腺功能紊乱，而且女性比男性更容易受到ATZ的伤害。这些影响是有组织的，并且在暴露结束很长时间后即可观察到。这些发现提醒了ATZ对非目标暴露生物（尤其是女性）的生长，代谢，繁殖和发育的副作用。