Focusing on the accumulation of chromatin/chromosomes around nucleoli and optimizing the timing of ICSI to facilitate the rescue in vitro maturation of denuded GV stage oocytes.

Purpose: This study aims to achieve the methodological improvement of rescue IVM by predicting germinal vesicle breakdown (GVBD) and optimizing the timing of ICSI.
Methods: Time lapse analysis was performed retrospectively to evaluated the relationship between the presence of AC around the nucleoli and GVBD. To find the optimal timing of ICSI, the time from the initiation of the first polar body extrusion to ICSI were measured, and the rates of fertilization at each point were calculated.
Results: The GVBD rate of GV stage oocytes with AC around the nucleoli was significantly higher than that of GV stage oocytes without AC. The GV stage oocytes required more time for nuclear maturation after polar body extrusion than MI oocytes, with GV stage oocytes taking 400-600 min from polar body extrusion to the optimal timing of ICSI, while the MI stage oocytes took 200-400 min. The GV stage oocytes resulted in the birth of healthy babies with the appropriate timing of ICSI.
Conclusion: It was found that GV stage oocytes with AC around nucleoli can initiate GVBD and reach the MII stage with a high rate, and that GV stage oocytes required more time than MI stage oocytes to reach the optimal timing of ICSI. Considering these factors, ART laboratories may employ immature GV stage oocytes in routine ART procedures rather than discarding them.
(© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)