Epigenetic effects on the embryo as a result of periconceptional environment and assisted reproduction technology  Emma Lucas  Reproductive BioMedicine Online  Volume 27, Issue 5, Pages 477-485 (November 2013) DOI: 10.1016/j.rbmo.2013.06.003 Copyright © 2013 Reproductive Healthcare Ltd. Terms and Conditions

Figure 1 During preimplantation development, the highly specialized oocyte and spermatozoon undergo extensive chromatin remodelling in order to achieve the appropriate nuclear packaging for the initiation of embryonic gene expression. DNA methylation and repressive histone modifications are removed during cleavage development and gradually replaced as the embryonic lineages begin to differentiate at the blastocyst stage. Active histone modifications coincide with the initiation of embryonic transcription. The dynamic nature of this very early developmental window makes it susceptible to perturbation, the consequences of which may have a significant impact on downstream development. Reproductive BioMedicine Online 2013 27, 477-485DOI: (10.1016/j.rbmo.2013.06.003) Copyright © 2013 Reproductive Healthcare Ltd. Terms and Conditions

Figure 2 Successful embryo development (and indeed development to adulthood) is influenced by numerous intrinsic and environmental factors. The combination of gamete quality, influenced by parental environment and genetics, and conception method will have immediate consequences on preimplantation development. The influence of the environment in utero may then modify the developmental trajectory in response to nutrient cues and other environmental effects. Interaction between these and other factors will ultimately determine developmental success. Reproductive BioMedicine Online 2013 27, 477-485DOI: (10.1016/j.rbmo.2013.06.003) Copyright © 2013 Reproductive Healthcare Ltd. Terms and Conditions