Abstract

Clarias gariepinus juveniles were exposed to environmentally relevant concentrations of 0 (control), 2.5, 25, 250 and 500 μg L⁻¹ atrazine in a quality-controlled 28-day laboratory procedure. Findings revealed a significant decrease in the levels of follicle-stimulating hormone, luteinizing hormone and prolactin relative to control (p < 0.05). Atrazine reduced the levels of testosterone while increasing the concentration of progesterone. Histologically, the control and treatments presented three stages of oocyte maturation: the chromatin nucleolar oocyte stage, early perinucleolar oocyte stage and the vitellogenic oocyte stage. However, in the ovaries of the treatment group with the lowest treatment concentration (2.5 μg L⁻¹), atretic oocytes with broken membranes invaded many of the dead ova and empty spaces. In other treatments (25, 250 and 500 μg L⁻¹), interfollicular spaces, vacuolation in oocyte formation, and dissolution of oocyte walls were observed. Disruption of the yolk vesicle and clumping of the cytoplasm in maturing oocytes was observed only at the highest atrazine concentration (500 μg L⁻¹). Gross alterations in ovarian histoarchitecture and reproductive hormone levels observed in this study showed interference with oogenesis which may result in reduced egg viability and fecundity in fish with ecological implications in water bodies exposed to atrazine even at reduced concentrations.

摘要

在质量控制的28天实验室程序中，将非洲胡子（Clarias gariepinus）少年暴露于环境相关浓度的0（对照），2.5、25、250和500μgL ^-1阿特拉津。研究结果表明，与对照组相比，促卵泡激素，促黄体生成素和催乳激素水平显着降低（p <0.05）。阿特拉津降低了睾丸激素的水平，同时增加了孕酮的浓度。从组织学上讲，对照和治疗呈现出卵母细胞成熟的三个阶段：染色质核仁卵母细胞阶段，早期核仁卵母细胞阶段和卵黄卵母细胞阶段。但是，在治疗组的卵巢中，治疗浓度最低（2.5μgL ^-1），膜破裂的闭锁卵母细胞侵入了许多死亡的卵和空的空间。在其他处理（25、250和500μgL ^-1）中，观察到卵泡间间隙，卵母细胞形成中的空泡化和卵母细胞壁的溶解。仅在最高r去津浓度（500μgL ^-1）下观察到成熟卵母细胞的卵黄囊泡破裂和细胞质团块。在这项研究中观察到的卵巢组织结构和生殖激素水平的总体变化表明，对卵子发生的干扰可能会导致鱼卵的活力和繁殖力下降，甚至降低浓度的阿特拉津水体也会对生态产生影响。