Morphological selection of oocytes
Non-invasive morphological evaluation of oocytes is a key routinary laboratory approach in the selection of the “best” gamete to be used for in vitro fertilization (IVF). This early selection may be useful in order to increase the overall effectiveness of assisted reproduction techniques (ART) and it may be especially helpful in case of legal/ethical restrictions in the production of supernumerary embryos. This review focuses on the state-ofart of the literature regarding egg morphological features predictive of embryo further development and viability, from the evaluation of Cumulus-Oocyte Complex (COC) to the assessment of nuclear and cytoplasmic maturity.
Investigated structures are namely COC, meiotic spindle, egg shape and volume, ooplasm texture, zona pellucida, perivitelline space and first polar body. Interestingly, only few morphological anomalies have been unanimously associated with embryo developmental competence, thus having a true prognostic value, the remaining being considered only phenotypic variants of unknown biological significance.
KEY WORDS: oocyte quality, morphologic evaluation, cumulus-oocyte-complex, meiotic spindle, first polar body, ooplasm texture, zona pellucida, perivitelline space.
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