Discrepancies between the effects of glutamine in cultures of preimplantation mouse embryos.

A review of the literature shows divergent differences between laboratories of the effects of glutamine in mouse preimplantation embryo culture media. One laboratory reported several cases of exencephaly, which was attributed to ammonia produced by the breakdown of glutamine. Two other laboratories have found no such effects. It is suggested, but not proved, that the differences in results may have a genetic basis. Further, it is argued that studies on the toxicological actions of exogenous ammonium chloride on preimplantation development provide a biased model of the effects of glutamine as used in embryo culture protocols. The finding that ammonium can also cause exencephaly thus fosters undue concern about the teratological effects of glutamine.