Effect of mouse strain on implantation rate of embryo transfer: A comparative study

AIM: To explore the relations of the strains of embryo and pseudopregnant recipient to live birth rate of embryo transfer and the feasibility of mixed transfer of different embryo strains. METHODS: A total of 362 embryos collected from 24 B6CF1 mice (F1 generation of Balb/c male and C578BL/6 emale mice) and 14 kunming (KM) mice were transferred into 24 mice of the 2 strains (8 B6CF1 mice and 16 KM mice)respectively for comparing the live birth rate. RESULTS: The birth rate of B6CF1 embryos transferred into the pseudopregnant mice of same strain were much higher (32.0%) than that of KM mice homogenous embryos (4.0%); the birth rate of mixed transferring of the 2 embryo strains were 25.0% of B6CF1 and 15.0% of KM mice. Except for homogenous embryo transfer, cross-strain embryo transfer was also performed in B6CF1 and KM mice. Among them, the total birth rate in embryo-transferred B6CF1 pseudopregnant mice (29.0%) was obviously higher than that in KM pseudopregnant mice (7.0%). As for embryo strain, the birth rate of B6CF1 strain embryo transferring (16.0%) was higher than that of KM embryo transferring (11.0%). CONCLUSION: The live birth rate of embryo transfer could be elevated by selecting mouse strain cautiously. Both cross-strain and mixed-strain embryo transfer are feasible, but homogenous embryo transfer is a priority. B6CF1 mouse is a better embryo transfer candidate than KM mouse.