Introduction: Intracytoplasmic sperm injection (ICSI) is a central procedure in assisted reproductive technologies. Its success depends not only on sperm quality and micromanipulation technique, but also on the structural and functional state of the oocyte. The oolemma is directly exposed to mechanical stress during penetration by the injection pipette, and its breakage pattern reflects membrane fluidity, elasticity, cortical cytoskeleton organization and the ability of the oocyte to tolerate micromanipulation. This pilot study investigated whether phosphatidylcholine, one of the major phospholipids of biological membranes, can modify the mechanical response of the human oocyte oolemma during ICSI-like penetration.

Materials and Methods: Human oocytes obtained within assisted reproductive technology programs were assessed at the GV, MI and MII stages. A total of 28 oocytes from four donors were initially evaluated; 24 viable oocytes were included in the final analysis. Oocytes were allocated into control and experimental groups according to maturation stage. Experimental groups were exposed for 30 minutes to L-alpha-phosphatidylcholine from soybean at a final concentration of 100 μM, while control groups were maintained under comparable culture conditions without phosphatidylcholine. Oolemma response was evaluated during standardized ICSI-like micromanipulation using an inverted Leica DMi8 microscope at 37 °C and classified according to the A-E typology of oolemma reaction.

Results: Primary penetration showed that immature GV and MI oocytes predominantly demonstrated type A oolemma reaction, whereas mature MII oocytes showed type B reaction. Four of the 28 initially assessed oocytes did not survive primary penetration, resulting in a final survival rate of 85.7%. In control groups, the oolemma reaction type remained unchanged after incubation. In experimental groups, phosphatidylcholine exposure produced a consistent directional shift: GV and MI oocytes changed from type A to type B, while MII oocytes changed from type B to type C. The differences between control and experimental groups were statistically significant for each maturation stage.

Conclusion: This study provides preliminary evidence that phosphatidylcholine can modify the mechanical behavior of the human oocyte oolemma during ICSI-like micromanipulation. The oolemma reaction type may serve as a functional marker of oocyte quality, while phosphatidylcholine may be considered a promising factor for further optimization of ICSI conditions and reduction of oocyte degeneration risk.