Developmental Potential of In Vitro Fertilization-Derived Mouse Zygotes Following Vitrification: Effects of...

Area of Science:

• Reproductive Biology
• Developmental Biology
• Genetically Modified Organisms

Background:

• Cryopreservation of mouse embryos is crucial for safeguarding genetically modified (GM) mouse strains and facilitating novel GM strain production.
• Superovulation is a key technique to maximize oocyte yield for in vitro fertilization (IVF) and subsequent embryo development.

Purpose of the Study:

• To compare the efficacy of anti-inhibin serum (AIS) and equine chorionic gonadotropin (eCG) for superovulation in C57BL/6J mice.
• To assess the developmental competence of embryos derived from AIS and eCG superovulation following vitrification and warming.
• To evaluate the in vitro and in vivo developmental potential of cryopreserved embryos from both superovulation methods.

Main Methods:

• Female C57BL/6J mice were superovulated using either AIS or eCG.
• Oocytes were inseminated via IVF to produce pronuclear stage embryos.
• Embryos were assessed for in vitro development to the blastocyst stage, cryopreserved via vitrification, and evaluated for post-warming integrity and developmental competence (in vitro and in vivo).
• Pregnancy and live birth rates were compared after transferring vitrified-warmed embryos into surrogate mothers.

Main Results:

• No significant difference was observed in the in vitro development to the 2-cell or blastocyst stage for fresh embryos derived from AIS or eCG superovulation.
• While the percentage of intact vitrified pronuclear embryos after warming differed between eCG and AIS, the subsequent in vitro development to the 2-cell and blastocyst stages was comparable.
• Pregnancy rates and live birth rates following the transfer of vitrified-warmed embryos were similar between the AIS and eCG superovulation groups.

Conclusions:

• Both AIS and eCG superovulation methods support comparable in vitro and in vivo embryonic development rates after vitrification and warming.
• AIS may be a preferred alternative to eCG for superovulation, particularly for mouse strains that yield fewer oocytes or embryos, aiding in GM mouse production and genome banking.
• The study validates the use of AIS as an effective superovulation agent for cryopreservation protocols in GM mouse strain management.