Epigenetic programming: from gametes to blastocyst.

Embryo development requires a series of cell fate decisions; cell lineages are established early during development and must be "remembered" through multiple cell divisions. It is increasingly evident that epigenetic marks, DNA methylation, histone modifications, and noncoding RNAs, have a critical role in this cell memory during development. During gametogenesis, epigenetic programming results in the production of spermatozoa and oocytes with distinctive chromatin. The goal of this article is to review what is known about the epigenetic marks in mature gametes and how these marks change during early embryo development. An understanding of the role of epigenetic programming during normal development will lay the basis for the elucidation of its role when development goes awry and the consequence is a birth defect.