Oocyte competency is the key to embryo potential

The oocyte is the major determinant of embryo developmental competence. Technology has improved the noninvasive assessment of oocyte quality. Analysis of polar body DNA may provide insight into the prediction of embryo developmental competence.

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David Keefe, M.D., Molly Kumar, M.D., Keri Kalmbach, M.S.

Volume 103, Issue 2, Pages 317-322


The oocyte is the major determinant of embryo developmental competence in women. It delivers half the chromosomal complement to the embryo, but the maternal and paternal genomes are neither symmetrical nor equal in their contributions to embryo fate. Unlike the paternal genome, the maternal genome carries a heavy footprint of parental aging. Indeed, age is the single best predictor of reproductive outcome in women, and the oocyte is the locus of reproductive aging in women. The oocyte transmits not only the mother’s nuclear but also her mitochondrial genome to the embryo, and mitochondrial DNA is known to be especially susceptible to aging. Morphological studies of the oocyte and its associated cumulus corona cells provide only marginal value in the assessment of embryo developmental potential. A number of novel technologies, however, have improved the noninvasive assessment of oocyte quality. Moreover, during maturation, the oocyte ejects half its homologous chromosomes into the first polar body and half its chromatids into the second polar body. Polar body DNA is remarkably similar to that of the oocyte, so analysis of polar body DNA provides a window into the oocyte’s genome and telomeres, which may enhance prediction of embryo developmental competence.

Read the full text at: http://www.fertstert.org/article/S0015-0282(14)02546-1/fulltext

Fertility and Sterility

Editorial Office, American Society for Reproductive Medicine

Fertility and Sterility® is an international journal for obstetricians, gynecologists, reproductive endocrinologists, urologists, basic scientists and others who treat and investigate problems of infertility and human reproductive disorders. The journal publishes juried original scientific articles in clinical and laboratory research relevant to reproductive endocrinology, urology, andrology, physiology, immunology, genetics, contraception, and menopause. Fertility and Sterility® encourages and supports meaningful basic and clinical research, and facilitates and promotes excellence in professional education, in the field of reproductive medicine.