[Hybridization between Mus musculus L. and Mus spretus Lataste under laboratory conditions (author's transl)]

2 species of mice Mus musculus brevirostris and Mus spretus are sympatric in Southern France and reproductively isolated. However, under laboratory conditions, they breed and give fully viable F 1 hybrids. This indicates that premating isolating mechanisms probably occur in nature and have yet to be investigated. Moreover, it now enables us to introduce new genetical markers in laboratory strains.