GLUCOSE, PYRUVATE, AND LACTATE CONCENTRATIONS IN THE BLASTOCOELE CAVITY OF RAT AND MOUSE EMBRYOS

The concentrations of glucose, pyruvate, and lactate have been measure d in the blastocoel fluid of single rat and mouse blastocysts, using t he technique of micropuncture combined with an ultramicrofluorescence assay. When cultured in the presence of 5.55 mM glucose, 11.5-12.5 mM L-lactate and 0.25-0.33 mM pyruvate, concentrations in the blastocoel fluid of mouse and rat were 2.30 and 2.75 mM glucose, 14.6 and 19.6 mM L-lactate, and 0.13 and 0.50 mM pyruvate, respectively. When cultured in the presence of 1.0 mM glucose and 1.0 MM L-lactate, concentration s in the blastocoel fluid were 0.50 and 0.59 mM glucose and 2.22 and 3 .70 MM L-lactate, respectively. These results suggest that (1) the bla stocyst is capable of maintaining considerable concentration gradients of substrates across the trophectoderm, (2) the microenvironment of t he blastocoel is adequately supplied with energy substrates for the de velopment of the inner cell mass, and (3) the inner cell mass is capab le of developing in both high and low glucose and lactate concentratio ns. (C) 1993 Wiley-Liss, Inc.