Purpose To investigate the relationship between meiotic spindle characteristics in human oocytes and the timing of the first zygotic cleavage after intracytoplasmic sperm injection (ICSI). Methods Zygotes that had cleaved to two-cell stage by 27 h post-ICSI were classified as early cleaving and the remainder as late cleaving. Meiotic spindle parameters previously imaged using the PolScope were compared between the two groups. Results Of 384 embryos, 163 were classed as early cleaving and 221 as late cleaving. The rate of blastocyst formation or pregnancy by Day 2 embryo transfer was significantly higher following early cleavage than after late cleavage (52.4% vs. 24.4% or 32.6% vs. 11.4%). Spindle areas (108.0 vs. 89.8 μm 2 ), lengths (14.7 vs. 13.4 μm) and PolScope retardance were also significantly greater in the early cleaving group. Conclusions Meiotic spindle parameters determine the timing of the first zygotic cleavage and are strong indicators of human embryo developmental potential.

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In previous studies, patients with severe peri-ovarian adhesions have been found to show low pregnancy rates and a poor response to gonadotrophin stimulation during in-vitro fertilization (IVF) treatment. The purpose of this retrospective pharmacokinetic study was to assess the diffusion of exogenous human chorionic gonadotrophin (HCG) in patients with peri-ovarian adhesions by examining the concentration of exogenous HCG in the follicular fluid in patients undergoing down-regulation and IVF due to infertility. The patients underwent laparoscopic examination for the scoring of peri-ovarian adhesions (using the classification of adnexal adhesions adopted by the American Fertility Society, a score of 0 means no adhesions, and a score of 32 represents bilateral expanded dense adhesions). Oocytes were recovered after human menopausal gonadotrophin-human chorionic gonadotrophin (HMG-HCG) stimulation with gonadotrophin-releasing hormone agonist. Serum and follicular fluid were collected at the time of oocyte recovery for measuring the HCG ratio (the follicular HCG concentration to the serum HCG concentration; a reflection of the diffusion of exogenous gonadotrophin) by time-resolved fluoroimmunoassay. A negative correlation was found between the number of oocytes recovered and the peri-ovarian adhesion score (r = -0.62, P < 0.01). In a given patient, the follicular HCG concentration was always lower than the serum HCG at the time of oocyte recovery. The HCG ratio in all samples was 0.9 or less (0.51 +/- 0.20; range, 0.09-0.90). Significant negative correlations were found between the peri-ovarian adhesion score and both the follicular HCG concentration (r = -0.80, P < 0.01) and the HCG ratio (r = -0.75, P < 0.01). In conclusion, severe peri-ovarian adhesions interfered with the diffusion of exogenous gonadotrophin into the follicular fluid during IVF treatment. Thus, the diffusion of exogenous gonadotrophin into the follicular fluid may represent a new parameter in the assessment of ovarian blood flow and IVF outcome.

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