Abstract
BACKGROUND: Genome-wide information on epigenetic modifications in mammalian preimplantation embryos was an unexplored sanctuary of valuable research insights protected by the difficulty of its analysis. However, that is no longer the case, and many epigenome maps are now available for sightseeing there. METHODS: This review overviews the current status of genome-wide epigenetic profiling in terms of DNA methylome and histone modifications in mammalian preimplantation embryos. MAIN FINDINGS: As the sensitivity of methods for analyzing epigenetic modifications increased, pioneering work began to explore the genome-wide epigenetic landscape in the mid-2010s, first for DNA methylation and then for histone modifications. Since then, a huge amount of data has accumulated, revealing typical epigenetic profiles in preimplantation development and, more recently, changes in response to environmental interventions. CONCLUSIONS: These accumulating data may be used to improve the quality of preimplantation embryos, both in terms of their short-term developmental competence and their subsequent long-term health implications.