Causes of developmental failure of in-vitro matured rhesus monkey oocytes: impairments in embryonic genome activation

Abstract

The relatively poor developmental competence of in-vitro matured primate oocytes is likely caused in part by failure in the timely onset of embryonic genome activation resulting from incomplete cytoplasmic maturation.

Waves of early transcriptional activation and pluripotency program initiation during human preimplantation development

“…It has been shown that asynchrony in the maternal to embryonic transition (Braude et al, 1988;Goddard and Pratt, 1983), which is often due to defective cytoplasmic maturation of the growing oocyte (Schramm et al, 2003), frequently results in developmental arrest. We report here the discovery of two waves of maternal mRNA turnover, which are tiled during early development.…”

Effects of in vitro maturation of monkey oocytes on their developmental capacity

“…Among the energy substrate triad, glucose alone was most effective in supporting cytoplasmic maturation of oocytes. Absence of glucose in the IVM medium, regardless of the presence of lactate and pyruvate, resulted in a dramatic reduction of development beyond the 8-cell stage, when the major zygote genome activation occurs in the rhesus monkey (Schramm et al, 2003), as it does in humans (Braude et al, 1988). These observations suggested the essential role of glucose in the events required for successful maternal to embryonic genome control transition.…”

“…Consequently, by oligo(dT) reverse transcription and PCR, we detected an overall greater amount of mRNAs and much less mRNA in oocytes and 2-cell embryos, respectively, from small nonstimulated follicles when compared to oocytes matured in vivo. Because the maternal store of mRNAs or proteins plays a crucial role in governing success of the maternal to embryonic transition, the precocious degradation of many maternal mRNAs could compromise the developmental potential of IVM oocytes from unstimulated small ovarian follicles, and thus explain why embryos derived from such oocytes fail to progress beyond the 8-cell stage when the major genome transition events occur in primates (Braude et al, 1988;Schramm and Bavister, 1999b;Schramm et al, 2003).…”

Morphology and Aneuploidy of in vitro Matured (IVM) Human Oocytes

“…Possible reasons include suboptimal IVM conditions as well as genetic and epigenetic characteristics of oocytes themselves. In many human and animal 6 to 8-cell IVM embryos, genome activation does not take place (Kim et al 2004;Schramm et al, 2003). This hindered embryo development is thought to be a consequence of disturbed cytoplasmic maturation or asyncronicity between the cytoplasmic and nuclear maturation in the oocyte.…”