Differential effect of hexoses on hamster embryo development in culture

The effects of glucose, fructose, and galactose on hamster embryo developme nt in the absence of phosphate were studied in culture. One- and two-cell e mbryos were cultured to the blastocyst stage in HECM-9 medium without hexos e or in medium with increasing concentrations of hexoses. Embryo developmen t, cell number, and cell allocation were assessed in blastocysts. Blastocys t viability was determined by transfer to pseudopregnant recipients. Althou gh 0.25 mM fructose increased mean cell number, low glucose concentrations had no stimulatory effect on development to blastocyst. Both galactose and 5.0 mM glucose were detrimental to embryos. Addition of 0.5 mM glucose incr eased implantation and fetal viability as compared with controls. Compared with 0.5 mM glucose, treatment with 0.25 mM fructose gave similar implantat ion and fetal viability, whereas 5.0 mM glucose tended to decrease implanta tion and significantly decreased fetal development. These data demonstrate that morphology is a poor indicator of embryo viability and that exposure o f preimplantation embryos to glucose or fructose is important for embryo vi ability post-transfer. Although no difference in blastocyst viability was d etected between embryos cultured with 0.25 mM fructose and those cultured w ith 0.5 mM glucose, increased cell numbers obtained with fructose suggest t hat fructose may be more appropriate than glucose for inclusion in culture medium.