Several studies suggest that exposure to environmental pollutants is partly responsible for testicular pathologies that have considerably increased over the last decades (cryptorchidism, hypospadias, cancer, decrease in the number of ejaculated spermatozoa). However, the cellular and molecular mechanisms involved in this reprotoxicity remain mostly unknown. One of the challenges of the european regulation REACH is to improve the knowledge on the chemical, toxic and ecotoxic properties of substances used in everyday life. As for the testicular toxicity, the few in vivo models used are not always the most appropriate for mechanistic studies. Our laboratory has developed and validated on a physiological point of view, coculture systems of germ cells in bicameral chambers, which reproduce a blood-testis barrier, allowing the determination of the mechanisms responsible for the toxicity of organic or mineral compounds on spermatogenesis, while reducing greatly the number of animals required.