The core glycosyltransferase families had already been established prior to the divergence of deuterostomes and protostomes, including Caenorhabditis elegans and Drosophila melanogaster. Approximately half of the glycosyltransferases found in Drosophila are orthologous to those in humans and participate in synthesizing glycan structures that are conserved across mammals. Developmental studies using Drosophila have demonstrated that these conserved glycans regulate multiple signaling pathways and play crucial roles in morphogenesis and cell fate determination. Similarly, in early mammalian development, these glycan structures are essential for regulating both cell fate decisions and differentiation. Studies using mouse embryonic stem (ES) cells have shown that glycans are involved in the maintenance of pluripotency and the specification of cell lineages. Furthermore, the expression patterns of glycosyltransferases and glycan structures undergo marked changes during the transition between pluripotent states corresponding to the earliest stages of mouse embryogenesis. Notably, more than 40% of these expression changes are directly regulated by the polycomb repressive complex 2 (PRC2), suggesting the presence of a comprehensive regulatory framework that governs the expression of glycosyltransferases and associated glycan structures during early development.