Donor oocyte dysmorphisms and their influence on fertilization and embryo quality

Abstract

The aim of this study was to identify predictors of fertilization rate (FR) and embryo quality (EQ) in 126 donor women who underwent 160 intracytoplasmic sperm injection (ICSI) cycles. Main outcome measures were oocyte dysmorphisms (OD) [perivitelline space (normal/large), perivitelline debris (no/yes), oocyte shape (spherical/non-spherical), zona pellucida (normal/abnormal), first polar body morphology (normal/fragmented or irregular), cytoplasmic granularity (normal/excessive), cytoplasmic vacuoles (no/yes) and colour of cytoplasm (normal/dark)], semen source (ejaculated or testicular), donor age, number of days of stimulation, plasma oestradiol concentration (pg/ml) on the day of human chorionic gonadotrophin administration, FR and day 2 EQ. No significant predictors of fertilization were identified. However, the presence of a dark cytoplasm decreased by 83% the likelihood of obtaining good quality embryos (OR=0.17; 95% CI: 0.04-0.74). Oocytes with a larger than normal perivitelline space were associated with 1.8 times higher chance of having good quality embryos (OR=1.80; 95% CI: 1.15-2.80). Patients and ovarian stimulation characteristics evaluated here did not affect FR and EQ. ICSI technique may guarantee good FR in spite of OD; however, certain cytoplasmic anomalies at the oocyte level, such as a dark cytoplasm, could compromise subsequent embryo development.

Significance of metaphase II human oocyte morphology on ICSI outcome

“…However, the majority of the oocytes retrieved after ovarian hyperstimulation exhibit one or more variations of the described ''ideal'' morphologic criteria (11-14, 20, 29, 41). This is true also for oocytes obtained from proven fertile donors (42). With the aim of identifying oocyte morphologic ''abnormalities'' of prognostic value for further development, 1,191 MII oocytes from 516 couples were analyzed in our laboratory before the ICSI procedure.…”

Intracytoplasmic Sperm Injection – Factors Affecting Fertilization

“…The repetitive organelle clustering is associated with an underlying adverse factor affecting the entire follicular cohort. The presence of a dark cytoplasm decreases by 83% the likelihood of obtaining good quality embryos [160]. However, another study did not find any adverse impact of dark colour of the oocytes on fertilization, embryo development and pregnancy rate [161].…”

Assessment of Mouse Germinal Vesicle Stage Oocyte Quality by Evaluating the Cumulus Layer, Zona Pellucida, and Perivitelline Space

“…Reports regarding the correlation between the size of the perivitelline space and embryo quality have been controversial. Studies reported that there is a correlation between the size of the perivitelline space, the presence of granulation, and subsequent embryo quality [23], [24], but not with implantation rates and clinical pregnancy [23]. However, another study found that the presence of coarse granules is associated with lower pregnancy and implantation rates [25].…”