Adapting the energy metabolism state to changing bioenergetic demands is essential for mammalian development accompanying massive cell proliferation and cell differentiation. However, it remains unclear how developing embryos meet the changing bioenergetic demands during the chorioallantoic branching (CB) stage when the maternal-fetal exchange of gases and nutrients is promoted. In this study, using metabolome analysis with mass-labeled glucose, we found that developing embryos redirected glucose carbon flow into the pentose phosphate pathway (PPP) via suppression of the key glycolytic enzymes PFK-1 and aldolase during CB. Concomitantly, embryos had increases in lactate pool size and in the fractional contribution of glycolysis to lactate biosynthesis. Imaging mass spectrometry (IMS) visualized lactate-rich tissues, such as the dorsal or posterior neural tube, somites, and head mesenchyme. Furthermore, we found that the heterochronic gene Lin28a could act as a regulator of the metabolic changes observed during CB. Perturbation of glucose metabolism rewiring by suppressing Lin28a downregulation resulted in perinatal lethality. Thus, our work demonstrates that developing embryos rewire glucose metabolism following CB for normal development
