Investigation of gene expression profiles before and after embryonic genome activation and assessment of functional pathways at the human metaphase II oocyte and blastocyst stage.

OBJECTIVE: To compare the oocyte versus the blastocyst transcriptome and provide data on molecular pathways before and after embryonic genome activation.
DESIGN: Prospective laboratory research study.
SETTING: An IVF clinic and a specialist preimplantation genetics laboratory. PATIENT(S): Couples undergoing or having completed IVF treatment donating surplus oocytes or cryopreserved blastocysts after patient consent. INTERVENTION(S): Sets of pooled metaphase II (MII) oocytes or blastocysts were processed for RNA extraction, RNA amplification, and analysis with the use of the Human Genome Survey Microarrays v2.0 (Applied Biosystems). MAIN OUTCOME MEASURE(S): Association of cell type and gene expression profile. RESULT(S): Totals of 1,909 and 3,122 genes were uniquely expressed in human MII oocytes and human blastocysts respectively, and 4,910 genes were differentially expressed between the two sample types. Expression levels of 560 housekeeping genes, genes involved in the microRNA processing pathway, as well as hormones and hormone receptors were also investigated. CONCLUSION(S): The lists of genes identified may be of use for understanding the processes involved in early embryo development and blastocyst implantation, and for identifying any dysregulation leading to infertility.