PRM2 and male infertility: Taking into account the fact that free radical generation is the basis of the genotoxic effect of Ni(II) and knowing that glutathione contributes to the reduction of damage to DNA, the primary aim of the study was to conclude whether male infertility caused by exposure to Ni(II) may be a result of oxidative stress affecting protamine 2 and whether rats being animals lacking protamine 2 are less sensitive to Ni(II), contrary to mice, which have that protein.