Quantitative evaluation of intercellular local deformation of human oocytes during Piezo-assisted intracytoplasmic sperm injection using video-based motion analysis

Abstract

Objective: To evaluate the relationship between the quantitative properties of local deformation of the ooplasm during Piezo-assisted intracytoplasmic sperm injection (Piezo-ICSI) and oocyte developmental fate after Piezo-ICSI.

Design: Video-based motion analysis and case-control study.

Setting: Private fertility center.

Patient(s): A total of 99 couples assigned to the standard Piezo-ICSI program.

Intervention(s): Video recordings of the sperm injection process during Piezo-ICSI.

Main outcome measure(s): Quantitative deformation properties consisting of the orientation of deformation perpendicular (Perp) or parallel (Para) to the oolemma and the mechanical response of the ooplasm (elongation, contraction, and total): Perp_-elongation, Perp_-contraction, Perp_-total, Para_-elongation, Perp_-contraction, and Para_-total.

Result(s): The deformation parameters were compared among different angular ranges of 30°-60°, 60°-90°, 90°-120°, and 120°-150° (defined as 0° at the 3 o'clock puncture site). The Perp_-total value at 30°-60° was significantly greater than that at the other angles (130.2 vs. 57.7-85.5, respectively) primarily due to substantially greater Perp_-elongation values. The Para_-total value at 30°-60° was significantly greater than that at the other angles (20.1 vs. 6.7-10.3, respectively) primarily due to substantially smaller Para_-contraction values. The deformation parameters of the ooplasm adjacent to the first polar body were also compared among different developmental fates (fertilization failure, cleavage arrest, and blastocyst development). The Perp_-total value of oocytes derived from blastocyst formation was significantly smaller than those derived from other developmental fates (58.1 vs. 70.0-87.3, respectively).

Conclusion(s): The Piezo-ICSI process induced deformation with various mechanical behaviors in different regions within a single oocyte. Furthermore, the exposure of the ooplasm adjacent to the first polar body to excessive deformation was found to be a possible trigger for adverse fertilization and embryo development after Piezo-ICSI.

Keywords: ICSI; Piezo; motion analysis; oocyte deformation; quantitative evaluation.