Messenger RNA in oocytes and embryos in relation to embryo viability

Messenger RNA (mRNA) expression techniques have become a powerful tool to analyze the relative abundance of transcripts related to oocyte and/or embryo quality. Numerous efforts to identify candidate genes for the developmental competence of bovine oocytes and embryos have been made employing different strategies. The preimplantation bovine embryo is initially under the control of maternal genomic information that is accumulated during oogenesis. Soon, the genetic program of development becomes dependent upon new transcripts derived from activation of the embryonic genome. The early steps in development including maturation, fertilization, timing of first cleavage, activation of the embryonic genome, compaction, and blastocyst formation can be affected by the culture media and conditions as well as the production procedure itself. These perturbations can possibly result in a dramatic decrease of the quality of the resulting blastocysts, and may even affect the viability of offspring born after transfer. (C) 2007 Elsevier Inc. All rights reserved.