Somatic and germline mosaicism in interspecific chimaeras between Mus musculus and Mus caroli

Detailed analysis of mosaicism in interspecific chimaeras between Mus musculus and Mus caroli revealed that cells of the two species could coexist and interact normally in all tissues studied. No selection occurred against M. caroli cells during gestation of chimaeras in the M. musculus uterus, but some tissue-specific differential growth of M. musculus and M. caroli cells occurred during postnatal development. Similar effects have, however, been reported in interstrain M. musculus chimaeras. The similarity between inter- and intraspecific chimaeric growth patterns supports the use of this interspecific system as a model for analysing cell lineage relationships during development.