Effects of glutamine and taurine on preimplantation development and cleavage of mouse embryos in vitro

Glutamine and taurine are reported to improve the development of mouse embryos in vitro, and glutamine is a component in CZB and KSOM, media optimized to overcome the 2-cell block in outbred strains of mice. Here we have studied the development of embryos from F-1 hybrid female mice in CZB and KSOM, from the zygote to the blastocyst stage, in the presence and absence of 1 mM glutamine and/or 5 mM taurine. Blastocyst formation, rate of development, number of trophectoderm and inner cell mass cells, mitosis, and cell death were examined. Glutamine had no effect on the proportion of embryos developing to the blastocyst stage, but it significantly reduced cell number at the blastocyst stage. The trophectoderm was the lineage most affected, showing increased levels of cell death. Changing the media after 48 h, to remove any possible buildup of toxic metabolites, did not reverse the inhibition by glutamine. Taurine had no effect on blastocyst development or cell number. Development in glutamine-free KSOM (KSOM-GIn) was compared to that in standard CZB and KSOM with glutamine and M16. Early cleavage was slower in M16, but by Day 5 over 84% of embryos had developed to the blastocyst stage in all media, with a similar cell number in M16, CZB, and KSOM. Cell numbers in blastocysts cultured in KSOM-GIn were significantly higher than in the other media and approached those found in vivo.