Assessment of Oocyte Quality
Assessment of oocyte morphology and determination of its correlation with quality/viability and the clinical outcome are difficult tasks, since the underlying mechanisms that change the appearance are multifactorial and complex. More than half of the oocy
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Assessment of Oocyte Quality Basak Balaban 13.1 Assessment of Oocyte Quality by Morphology – 124 13.2 Morphological Deviations of Mature Metaphase II Stage Human Oocytes – 124 13.2.1 Cytoplasmic Abnormalities – 124 13.2.2 Extracytoplasmic Abnormalities – 127
13.3 Conclusions – 129 Review Questions – 130
References – 130
© Springer Nature Switzerland AG 2019 Z. P. Nagy et al. (eds.), In Vitro Fertilization, https://doi.org/10.1007/978-3-319-43011-9_13
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B. Balaban
Learning Objectives 55 The maturity stage of the oocyte is of major importance for the successful fertilization outcome after in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). Visualization of the morphological appearance of mature metaphase II stage (MII) oocyte may also play an important role on the clinical outcome specifically for ICSI cycles at which the cumulus-corona cells are removed before the fertilization procedure. 55 The objective of this chapter is to provide an overview of the effect of morphological deviations of MII oocytes on the clinical success in assisted reproduction.
Key Points
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The deviations that should be examined with high priority are in the following order: 55 Oocytes that are large in size (giant oocytes) and oocytes that have a large first polar body should not be used for insemination because of the high risk of chromosomal abnormalities. If the patient has only such oocytes, preimplantation genetic screening of the derived embryo can be recommended. 55 Oocytes should be observed for the presence of smooth endoplasmic reticulum cluster/s within the cytoplasm. The patient should be informed that embryos derived from such oocytes may have significantly reduced rates of healthy offspring. 55 Oocytes should be observed for the presence of vacuole/s within the cytoplasm. Patients should be informed that MII oocytes with vacuole(s) ≥14 μm have a significantly lower chance of getting fertilized when compared with oocytes with a normal morphological appearance. 55 Oocytes should be observed for the presence of organelle clustering/centrally located condensed granulation within the cytoplasm. The patient should be informed that embryos derived from such oocytes may have a higher risk of chromosomal abnormalities. 55 Oocytes defined with other cytoplasmic deviations such as refractile bodies/cytoplasmic inclusions or with dark cytoplasm/dark cytoplasm-granular cytoplasm/dark cytoplasm with slight granulation/ dark granular appearance of the cytoplasm/diffused cytoplasmic granularity should be documented. 55 Ovoid oocytes with ovoid zona and normally shaped oolemma or ovoid zona and ovoid oolemma should be observed as the blastocyst formation rate of embryos derived from such oocytes may be detrimentally affected and delayed. 55 Oocytes with extremely large perivitelline space (PVS) may result in reduced fertilization rates and higher degeneration rates following ICSI. 55 Dysmorphic zona pellucida, discoloration of the oocyte, first polar body morphology, and debris in PVS should be docu
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