Description:
<jats:title>ABSTRACT</jats:title><jats:p>Artificial insemination has been used to produce interspecific mouse hybrids. Mus musculus × Mus cervicolor cervicolor hybrids failed to complete more than a few cleavage divisions but both M. musculus × M. dunni and M. musculus × M. caroli hybrids completed preimplantation development. These hybrid embryos are heterozygous for various X-linked enzymes and may provide a useful genetic system for studying X-chromosome inactivation during early development. Further development of M. musculus × M. caroli hybrids was studied: several completed foetal development; a few survived to maturity but none has yet reproduced.</jats:p>