Since amphibians are recognised as good models to assess the quality of environments, only few studies have dealt with the impacts of chemical contaminants on their gametes, while toxic effects at this stage will alter all the next steps of their life cycle. Therefore, we propose to investigate the oocyte maturation of Xenopus laevis in cadmium- and lead-contaminated conditions.

The impacts of cadmium and lead ions were explored on events involved in the hormone‐dependent process of maturation. In time-course experiments, cadmium, at the highest concentration, delayed and prevented the germinal vesicle breakdown. Even in the absence of progesterone this ion could also induce it. No such spontaneous maturation was observed after lead exposures. An acceleration of the process at the highest tested concentration of lead (90 μM), in presence of progesterone, was recorded. Cytological observations highlighted that cadmium exposures drove severe disturbances of meiotic spindle morphogenesis. At last, cadmium exposures altered the MAPK pathway, regarding the activation of ERK2 and RSK, but also the activation and the activity of the MPF, by disturbing the state of phosphorylation of Cdc2 and histone H3.

Xenopus laevis oocytes were affected by these metal ion exposures, notably by Cd²⁺. Signatures of these metal exposures on the oocyte maturation were detected. This germ cell appeared to be a relevant model to assess the effects of environmental contaminants such as metals.

由于两栖动物被认为是评估环境质量的良好模型，因此很少有研究处理化学污染物对其配子的影响，而在这一阶段的毒性影响将改变其生命周期的所有后续步骤。因此，我们建议研究镉和铅污染条件下非洲爪蟾的卵母细胞成熟。

探讨了镉和铅离子对激素依赖的成熟过程所涉及事件的影响。在时程实验中，最高浓度的镉延迟并阻止了生发囊泡的破裂。即使没有孕酮，该离子也可能诱导它。铅暴露后未观察到这种自发成熟。在孕酮存在下，在铅的最高测试浓度（90μM）下记录了过程的加速。细胞学观察结果突出表明，镉暴露导致减数分裂纺锤体形态发生的严重紊乱。最后，镉暴露通过扰乱Cdc2和组蛋白H3的磷酸化状态，改变了EAPK2和RSK活化的MAPK途径，也改变了MPF的活化和活性。

非洲爪蟾卵母细胞受到这些金属离子暴露的影响，特别是受Cd ^2+的影响。检测到这些金属暴露对卵母细胞成熟的影响。该生殖细胞似乎是评估环境污染物（例如金属）影响的相关模型。