Assessment of Oocyte and Early Embryo Morphology with Regard to Embryonic Development and the Outcome of Assisted Reproduction
Ovarian hormone stimulation is accompanied in most assisted reproduction therapies by the monitoring of follicular growth using ultrasonographic investigations. In addition, the amount of estrogen and luteinizing hormone in peripheral blood plasma is assessed to determine the optimal time for ovulation induction. The therapeutic goal is to achieve an appropriate number of mature oocytes, for example, for in vitro fertilization or intracytoplasmic sperm injection (ICSI), because these seem to guarantee superior-quality embryos. However, well-monitored ovarian stimulation does not necessarily always guarantee mature oocytes. Since no reliable biochemical tests are available to assess follicular fluid components in the punctured fluid material, direct microscopic assessment of the morphology of the oocytes remains the most practical and promising method of evaluation. This assessment leads to a scoring of the oocyte and the resulting embryos, which bears a relation to the subsequent pregnancies. The use of a widely accepted score and photo/video documentation would be an accurate base for a comparison between different laboratories. The cumulus-oocyte complex, which has to be seen as a functional unit, contains the cumulus cells, the densely packed corona radiata cells, and the oocyte itself with the zona pellucida (Fig. 1).
KeywordsEmbryo Transfer Zona Pellucida Preimplantation Genetic Diagnosis Polar Body Blastocyst Stage
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