Effects of macromolecules recovered from uterine luminal fluid on the metabolism of [U-14C]glucose by mouse morulae and early blastocysts in vitro.

Day-4 mouse embryos grew well in culture media supplemented with macromolecular components of uterine fluids recovered on day 3, 4 or 5 of pregnancy and pseudopregnancy. Addition of these components to media during a 2-h pulse culture had no significant effect on the incorporation of glucose carbon by morulae/early blastocysts. However, various fractions of uterine luminal macro-molecules significantly increased the turnover of glucose carbon incorporated into acid-soluble and acid-insoluble glycogen, into nucleic acids and into proteins during a 24-h chase culture. These effects were due mainly to components with a molecular weight between 1000 and 10,000 Da and the activity was most marked in fluids collected on day 5 of pregnancy or pseudopregnancy. Oxidation of glucose during a 4-h incubation was inhibited in the presence of certain uterine macromolecules but most consistently by the large molecular weight component (greater than 300,000 Da). Some differences were noted in the inhibitory activity of macromolecules obtained from pregnant and pseudopregnant sources. There was little evidence of an effect of uterine-fluid components on lactate production from glucose.