Interspecific hybrids and chimeras in mice.

Area of Science:

• Developmental Biology
• Immunology
• Genetics

Background:

• Mammalian interspecific hybrids and chimeras are valuable for studying genetics and embryology.
• Mus musculus (laboratory mouse) and Mus caroli (wild mouse) typically do not interbreed.

Purpose of the Study:

• To produce hybrids and chimeras between Mus musculus and Mus caroli.
• To investigate the causes of poor hybrid survival and identify the role of trophoblast-uterine interactions.

Main Methods:

• Artificial insemination to produce sterile hybrids.
• Transfer of Mus caroli blastocysts into Mus musculus uterus.
• Injection of Mus caroli inner cell mass into Mus musculus blastocysts.
• Trophoblast vesicle reconstitution.
• In situ hybridization using a Mus musculus satellite DNA probe.

Main Results:

• Mus caroli blastocysts had poor survival in the Mus musculus uterus, associated with maternal T-cell cytotoxic responses.
• Mus caroli inner cell mass cells survived and developed to term when injected into Mus musculus blastocysts, forming viable chimeras.
• Trophoblast vesicle reconstitution yielded viable Mus caroli offspring.
• Mus caroli trophoblast may possess distinct antigenic and immunosuppressive properties compared to Mus musculus.

Conclusions:

• Trophoblast-uterine interactions are critical for interspecific pregnancy success in mammals.
• Maternal immune responses and trophoblast properties significantly influence embryonic survival across species.
• Interspecific chimeras provide a powerful model for studying developmental biology and cell lineage.