3 A Role for Fructose Metabolism in Development of Sheep and Pig Conceptuses Robyn M. Moses, Avery C. Kramer, Heewon Seo, Guoyao Wu, Gregory A. Johnson, and Fuller W. Bazer Abstract The period of conceptus (embryo and extraem- bryonic membrane) development between fer- tilization and implantation in mammalian species is critical as it sets the stage for placental and fetal development. The trophectoderm and endoderm of pre-implantation ovine and por- cine conceptuses undergo elongation, which requires rapid proliferation, migration, and morphological modification of the trophecto- derm cells. These complex events occur in a hypoxic intrauterine environment and are sup- ported through the transport of secretions from maternal endometrial glands to the conceptus required for the biochemical processes of cell proliferation, migration, and differentiation. The conceptus utilizes glucose provided by the mother to initiate metabolic pathways that provide energy and substrates for other meta- bolic pathways. Fructose, however, is in much greater abundance than glucose in amniotic and allantoic fluids, and fetal blood during preg- nancy. Despite this, the role(s) of fructose is largely unknown even though a switch to fructosedriven metabolism in subterranean rodents and some cancers are key to their adaptation to hypoxic environments. Keywords Pregnancy Á Glucose Á Fructose Á Conceptus Development Abbreviations BNC Binucleated trophoblast giant cells DHAP Dihydroxyacetone phosphate ESR1 Estrogen receptor a F1P Fructose-1-phosphate F6P Fructose-6-phosphate G6P Glucose-6-phosphate G6PDH Glucose-6-phosphate dehydrogenase GAP Glyceraldehyde-3-phosphate HIF1A Hypoxia inducible factor-1a IFNT Interferon tau KHK Ketohexokinase LE Luminal epithelia NAD + / NADH Nicotinamide adenine dinucleotide NADP + / NADPH Nicotinamide adenine dinucleotide phosphate OXTR Oxytocin receptor PFK Phosphofructokinase-1 PGF2a Prostaglandin F 2a PHGDH Phosphoglycerate dehydrogenase PPP Pentose phosphate pathway R. M. Moses Á A. C. Kramer Á H. Seo Á G. Wu Á G. A. Johnson Á F. W. Bazer (&) Departments of Animal Science and Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843, USA e-mail: fbazer@cvm.tamu.edu © Springer Nature Switzerland AG 2022 G. Wu (ed.), Recent Advances in Animal Nutrition and Metabolism, Advances in Experimental Medicine and Biology 1354, https://doi.org/10.1007/978-3-030-85686-1_3 49