Cumulus Cell Gene Expression in Assessment of Oocyte Quality
Cumulus cells originate from granulosa cells and surround oocytes from the time of follicular antrum formation until after fertilization. The cumulus cells have essential functions in the ovary, mediating transmission of endocrine signals and supporting oocyte growth and maturation. The relationship between oocytes and their associated cumulus cells is extremely intimate. Cytoplasmic projections extend from the innermost layer of cumulus cells, penetrating the zona pellucida and forming gap junctions at the oocyte surface. This allows for direct exchange of macromolecules, a bidirectional communication essential for the production of competent oocytes. The fact that cumulus cells are so closely associated with the oocyte, and share the same microenvironment within the ovary, has led to suggestions that information concerning oocyte quality might be obtained by analyzing them. Several studies focused on cumulus cell gene expression have now been published, indicating that a noninvasive assessment of oocyte potential, based upon analysis of the surrounding cumulus cells, may indeed be possible.
KeywordsHuman Oocyte Cumulus cells Transcriptome Gene expression
Dagan Wells is funded by NIHR Biomedical Research Centre Program.
Cases where fewer mRNA transcripts are found. Gene expression is reduced (i.e., the gene is less active).
A complete set of all of the genes (i.e., the entire genome) is present in all cells. However, only a fraction of these genes are active in a cell at any given moment. Genes which are being actively transcribed, producing mRNA and ultimately proteins, are said to be “expressed.”
A method for simultaneously quantifying the number of transcripts from large numbers of genes (typically thousands or tens of thousands of genes simultaneously assessed).
transcripts The molecules that serve as intermediates between genes (made of deoxyribonucleic acid, DNA) and the proteins they produce. The DNA sequence of a gene is transcribed into a messenger RNA (ribonucleic acid) copy, which is subsequently translated into a polypeptide.
A method of quantifying the number of mRNA transcripts from individual genes. Real-time PCR is generally considered the most accurate method for quantifying gene expression but only allows analysis of small numbers of genes at a time.
The sum total of all mRNA transcripts found within an individual cell or tissue. The characterization of the transcriptome reveals all of the genes expressed (i.e., active).
When two different samples are compared, some genes may be found to have differences in the number of mRNA transcripts. If a sample contains a greater number of mRNA transcripts than expected, the gene is said to be upregulated or overexpressed (i.e., it is more active).
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