In vitro analysis of glucose metabolism and embryonic growth in postimplantation rat embryos.

The glucose metabolism and embryonic development of rat embryos during organogenesis was studied using embryo culture. Glucose uptake and embryonic growth and differentiation of 10.5-day explants (embryos + membranes) were limited by the decreasing glucose concentration, but not the increasing concentration of metabolites, in the culture media during the second 24 h of a 48 h culture. No such limitations were found on the embryonic development of 9.5-day explants during a 48 h culture although glucose uptake was slightly reduced at very low concentrations of glucose. From the head-fold stage to the 25-somite stage of development, glucose uptake was characteristic of the stage of development of the embryo and not the time it had been in culture. Embryonic growth of 9.5-day explants was similar to that previously observed in vivo. Glucose uptake by 9.5-day explants was dependent on the surface area of the yolk sac and was independent of the glucose concentration in the culture media (within the range of 9.4 to 2.5 mM). The proportion of glucose converted to lactate was 100% during the first 42h of culture then fell to about 50% during the final 6h. The protein contents of both the extraembryonic membranes and the embryo were dependent on the glucose uptake.