Effects of Medium Enrichment with Amino Acids on the Results of in vitro Embryo Culture and Embryo Transfer in Mice

The widespread use of modern reproductive technologies in medicine stimulates the improvement of in vitro culture systems for preimplantation embryos. The question of whether to choose relatively simple media or media enriched with amino acids, vitamins, and other components for embryo culture is not only of practical importance for reproductive medicine but also crucial for designing adequate experiments in mice. This study compared the effects of short-term in vitro culture of C57BL/6 mouse embryos in a simple medium (KSOM) and an amino acid-enriched medium (KSOMaa) on the rates of in vitro development and implantation frequency after embryo transfer, as well as on the body weight in offspring during the suckling period. No differences in the rates of in vitro development were found when cleavage-stage mouse embryos were cultured for 27 h in either media, which may be due to the short duration of the procedure. After 27 h of in vitro culture in both media, the majority of embryos reached the blastocyst stage. However, some of them were developmentally delayed and remained at the compact-morula stage, while some degraded. Meanwhile, differences were observed during the subsequent in vivo development of such embryos. After embryo transfer, implantation occurred more frequently in embryos cultured in vitro in the amino acid-enriched KSOMaa medium. During the suckling period, the body weight in offspring did not differ between the groups. Thus, enrichment of a culture medium with amino acids during a relatively short-term in vitro culture of cleavage-stage mouse embryos increases the implantation rate after embryo transfer.