Related Experiment Videos
Cryopreservation of strains and mutant genes in mice
A Yoshiki1, K Ohno, N Wakasugi
1Laboratory of animal genetics, School of Agriculture, Nagoya University, Japan.
Abstract:
Three kinds of freezing methods were tested with embryos of DNI strain. The survival rate after thawing was 47.5%, 66.7% and 77.8% in the 2-step method, modified slow freezing method and modified 2-step method, respectively. Then, the modified 2-step method was applied to the embryos from 7 strains and a pair of interstrain crosses. PMSG treatment at the beginning of diestrus following HCG treatment after 48 hrs resulted in much yield of 8-16-cell embryos in all strains. The average number for each strain was as follows: DNI; 18.9, DDN; 13.0, BS; 20.4, C57BL/6; 12.9, DBA/2; 17.5, CRN; 19.8, PAN; 13.7 and DNI x C57BL/6-Ay; 21.7. Development of frozen-thawed embryos in culture varied among strains. Proportion of embryos that developed to the morula or blastocyst stage was as follows: DNI; 64.6%, DDN; 71.9%, BS; 53.6%, C57BL/6; 57.3%, DBA/2; 65.0%, CRN; 52.5%, PAN; 17.4% and DNI x C57BL/6-Ay; 44.1%. These results indicate that the ability of embryos to survive freezing and thawing is influenced by their genetic background. Live young were produced from DNI, DDN, BS and DNI x C57BL/6-Ay embryos after transfer to recipients. Comparative assessment of the developmental ability of frozen-thawed embryos after transfer among strains should be performed in further study.
Insights
The modified 2-step freezing method significantly improved embryo survival rates. Embryo cryopreservation success varies by genetic background, impacting post-thaw development and live birth potential.
Area of Science:
- Reproductive Biology
- Cryobiology
- Genetics
Background:
- Cryopreservation of embryos is crucial for assisted reproductive technologies and genetic resource preservation.
- Optimizing freezing protocols is essential to maximize post-thaw viability and developmental potential.
Purpose of the Study:
- To evaluate and compare the efficacy of different embryo freezing methods.
- To assess the impact of genetic background on embryo cryosurvival and developmental competence after thawing.
- To determine optimal hormonal treatments for maximizing embryo yield for cryopreservation.
Main Methods:
- Three freezing methods (2-step, modified slow freezing, modified 2-step) were tested on DNI strain embryos.
- The most effective method (modified 2-step) was applied to embryos from seven strains and one interstrain cross.
- Hormonal treatments (PMSG and HCG) were used to stimulate superovulation and maximize 8-16 cell embryo yield.
Main Results:
- The modified 2-step freezing method yielded the highest survival rate (77.8%) after thawing.
- Embryo development to morula/blastocyst stages post-thaw varied significantly among strains, ranging from 17.4% to 71.9%.
- Live young were successfully produced from cryopreserved embryos of specific strains (DNI, DDN, BS, DNI x C57BL/6-Ay) after transfer.
Conclusions:
- The modified 2-step freezing protocol enhances embryo cryosurvival.
- Embryo cryosurvival and developmental competence are significantly influenced by the genetic background of the strain.
- Further studies are needed to compare post-transfer developmental abilities across different strains.