Human oocyte cytometry and fertilisation rate after subzonal insemination

Area of Science:

• Reproductive biology and assisted reproductive technologies (ART).
• Oocyte and sperm morphology and function analysis.
• In vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) research.

Background:

• Subzonal insemination (SUZI) is an ART technique used to overcome male infertility.
• Oocyte quality, including size and nuclear maturity, is critical for successful fertilization.
• The impact of oocyte diameter and zona pellucida thickness on SUZI outcomes requires further investigation.

Purpose of the Study:

• To evaluate the cytometry of oocytes during subzonal insemination (SUZI).
• To investigate the correlation between oocyte diameter, zona thickness, and fertilization rates.
• To assess the influence of different sperm defects on oocyte characteristics and SUZI success.

Main Methods:

• Cytometric analysis of 545 oocytes from 85 SUZI attempts.
• Measurement of oocyte and oolemma diameters and zona thickness on days 0, 1, and 2.
• Comparison of fertilization rates based on oocyte size and specific sperm defect indications for SUZI.

Main Results:

• Oocyte diameter increased significantly between day 0 and day 1.
• Smaller oocytes (<108 microns) showed significantly lower fertilization rates (9.8%) compared to larger oocytes (>108 microns) (21.2%).
• Oocytes from non-specific sperm defect groups had smaller diameters; LODA and antisperm antibody groups had thicker zona pellucida.

Conclusions:

• Oocyte diameter and zona pellucida thickness are significant factors influencing fertilization success in SUZI.
• Oocyte growth post-retrieval is important for fertilizing ability.
• These findings suggest that oocyte size and zona characteristics, beyond nuclear maturity, are vital for ART outcomes.