Sperm deposition site during ICSI affects fertilization and development.

Area of Science:

• Reproductive Medicine
• Embryology
• In Vitro Fertilization

Background:

• Intracytoplasmic sperm injection (ICSI) is a key technique in assisted reproductive technology.
• The precise placement of sperm during ICSI relative to the oocyte's meiotic spindle is crucial for successful fertilization and development.
• Understanding optimal sperm deposition sites can enhance ICSI outcomes.

Purpose of the Study:

• To investigate the impact of sperm placement during ICSI on fertilization and preimplantation embryo development.
• To determine if specific sperm deposition sites relative to the M-II spindle influence embryo quality and implantation rates.

Main Methods:

• Retrospective analysis of 776 patients undergoing ICSI within an IVF-ET program.
• Recording of oocyte quality, sperm deposition site, and polar-body position during ICSI.
• Assessment of fertilization on day 1 and embryo development on days 2 and 3.

Main Results:

• Sperm placement at the 7 or 11 o'clock positions relative to the polar body yielded the highest number of high-quality embryos.
• Fertilization rates were generally unaffected, except for a lower rate when the polar body was at 9 o'clock.
• Embryos from the 7 or 11 o'clock sperm deposition group showed a trend towards higher implantation rates.

Conclusions:

• Sperm placement during ICSI significantly influences fertilization and high-quality embryo development.
• Avoiding direct sperm injection into the M-II spindle area is recommended.
• Reducing the distance between the sperm and the spindle appears to improve embryo development rather than fertilization itself.