Development of assisted reproductive technologies for Mus spretus†

Area of Science:

• Reproductive Biology
• Animal Science
• Genetics

Background:

• The genus Mus exhibits high genetic diversity, but Mus musculus is the primary species used in research.
• Limited availability of assisted reproductive technologies (ARTs) restricts the use of other Mus species, like Mus spretus, in laboratories.

Purpose of the Study:

• To devise practical ARTs for Mus spretus (Algerian mouse) to facilitate their use in biomedical research.
• To address challenges in in vitro embryo production and establish efficient methods for embryo cryopreservation and interspecific transfer.

Main Methods:

• Investigated superovulation efficacy using equine chorionic gonadotropin and anti-inhibin serum (AIS).
• Performed in vitro fertilization (IVF) and reciprocal IVF with Mus musculus to identify fertilization barriers.
• Optimized hormone treatments (AIS, hCG, estradiol) combined with natural mating for in vivo embryo production.
• Utilized vitrification and warming techniques for cryopreservation of embryos.
• Conducted interspecific embryo transfer into (C57BL/6 × C3H) F1 female mice.

Main Results:

• In vitro production of Mus spretus embryos showed low efficacy due to zona pellucida hardening and low IVF rates (15.2%).
• A combination of AIS, hCG, and estradiol injections followed by natural mating yielded the highest number of in vivo-derived embryos (16 per female).
• Vitrification/warming of these embryos resulted in a high survival rate (94%).
• Over 60% of transferred embryos developed into healthy offspring, demonstrating successful interspecific embryo transfer.

Conclusions:

• Practical ARTs for Mus spretus have been successfully developed, enabling efficient embryo production and animal generation.
• These ARTs facilitate safe laboratory preservation of Mus spretus strains.
• The study demonstrates the feasibility of interspecific embryo transfer in murine rodents.