Current and future contributions of transgenic mice to the analysis of germline toxicology.

Evermore sophisticated tests are need to study germline toxicology. The gene conversion-based systems developed in Leicester and in the USA are steps in the right direction, but a lot of validation both in vivo and in vitro is required. Transgenic technology can also be used to research the biology of testis, so that we know more how to make it more human-like. If you talk to toxicologists, they always complain: ‘but it’s only a rat, it’s only a mouse, it’s not a man’. In future, once we understand more biology - it might be possible to make the toxicological response of a transgenic mouse more human-like. As we all know, the testis is a complex biological system and it is only when we get a better understanding of what is going on to the fundamental level are such developments possible. Indeed, it might be possible to do even more exciting things, such as taking mitotic human tissue culture cells and to inducing them to enter meiosis in vitro. Such a system would be a natural complement to the in vitro tests widely used in industry.