Artificial removal of the zona pellucida at the pronuclear stage: an exploratory study to improve embryo fragmentation

Objective: To investigate whether artificial removal of zona pellucida (ZP) at the pronuclear stage improves good-quality embryos and blastocyst development in patients with difficulty conceiving because of severe fragmentation in early-cleavage stage. Design: Exploratory investigation. Setting: Rep...

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Main Authors: Keitaro Yumoto, B.Sc., Toko Shimura, B.Sc., Minori Kawamoto, M.Sc., Minako Sugishima, B.Sc., Yasuyuki Mio, M.D., Ph.D.
Format: Article
Language:English
Published: Elsevier 2024-12-01
Series:F&S Reports
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Online Access:http://www.sciencedirect.com/science/article/pii/S2666334124000928
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author Keitaro Yumoto, B.Sc.
Toko Shimura, B.Sc.
Minori Kawamoto, M.Sc.
Minako Sugishima, B.Sc.
Yasuyuki Mio, M.D., Ph.D.
author_facet Keitaro Yumoto, B.Sc.
Toko Shimura, B.Sc.
Minori Kawamoto, M.Sc.
Minako Sugishima, B.Sc.
Yasuyuki Mio, M.D., Ph.D.
author_sort Keitaro Yumoto, B.Sc.
collection DOAJ
description Objective: To investigate whether artificial removal of zona pellucida (ZP) at the pronuclear stage improves good-quality embryos and blastocyst development in patients with difficulty conceiving because of severe fragmentation in early-cleavage stage. Design: Exploratory investigation. Setting: Reproductive center. Patient(s): Thirty-four patients scheduled for assisted reproductive technology (ART) treatment in our clinic between February 2020 and January 2021 were selected to undergo ZP removal according to their ART-related medical history. In total, 173 two pronuclei zygotes were obtained, with 101 allocated to the ZP-free group and 72 to the ZP-intact group. All patients had zygotes allocated in both ZP-free and ZP-intact groups. Intervention(s): Oocytes that were confirmed to be normally fertilized were placed in sucrose-containing HEPES medium for approximately 5 minutes and cultured under one of the following two conditions: ZP-free, in which the ZP was completely removed from the ooplasm by laser irradiation and a medium-blowing method with a biopsy pipette; and ZP-intact. Subsequently, embryos were either freshly transferred on day 2 (ZP-intact group only, according to patients’ wishes), or day 5/6, or they were cryopreserved on day 5/6/7 for future embryo transfer cycles for both groups. Main Outcome Measure(s): Rates of good-quality embryos, blastocyst development, morphologically good-quality blastocyst development, and cryopreservation. Result(s): In ZP-free embryos, the inter-blastomere adhesion was not disturbed and the fragmentation was significantly decreased that resulted into significant improvement in all measured parameters compared with the ZP-intact group. Conclusion(s): Artificial ZP removal at the pronuclear stage may prevent excessive fragmentation leading to good-quality blastocysts. Moreover, patients with recurrent ART failure may achieve successful pregnancies.
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spelling doaj-art-e2c1b3484aac4db48ee8dcbddf60f2fb2025-08-20T01:56:39ZengElsevierF&S Reports2666-33412024-12-015438539310.1016/j.xfre.2024.08.011Artificial removal of the zona pellucida at the pronuclear stage: an exploratory study to improve embryo fragmentationKeitaro Yumoto, B.Sc.0Toko Shimura, B.Sc.1Minori Kawamoto, M.Sc.2Minako Sugishima, B.Sc.3Yasuyuki Mio, M.D., Ph.D.4Reproductive Center, Medical Corporation Group Mio Fertility Clinic, Kuzumo-Minami, Yonago, JapanReproductive Center, Medical Corporation Group Mio Fertility Clinic, Kuzumo-Minami, Yonago, JapanReproductive Center, Medical Corporation Group Mio Fertility Clinic, Kuzumo-Minami, Yonago, JapanReproductive Center, Medical Corporation Group Mio Fertility Clinic, Kuzumo-Minami, Yonago, JapanReproductive Center, Medical Corporation Group Mio Fertility Clinic, Kuzumo-Minami, Yonago, Japan; Correspondence: Yasuyuki Mio, M.D., Ph.D., Reproductive Center, Medical Corporation Group Mio Fertility Clinic, 2-1-1, Kuzumo-Minami, Yonago 683-0008, Japan.Objective: To investigate whether artificial removal of zona pellucida (ZP) at the pronuclear stage improves good-quality embryos and blastocyst development in patients with difficulty conceiving because of severe fragmentation in early-cleavage stage. Design: Exploratory investigation. Setting: Reproductive center. Patient(s): Thirty-four patients scheduled for assisted reproductive technology (ART) treatment in our clinic between February 2020 and January 2021 were selected to undergo ZP removal according to their ART-related medical history. In total, 173 two pronuclei zygotes were obtained, with 101 allocated to the ZP-free group and 72 to the ZP-intact group. All patients had zygotes allocated in both ZP-free and ZP-intact groups. Intervention(s): Oocytes that were confirmed to be normally fertilized were placed in sucrose-containing HEPES medium for approximately 5 minutes and cultured under one of the following two conditions: ZP-free, in which the ZP was completely removed from the ooplasm by laser irradiation and a medium-blowing method with a biopsy pipette; and ZP-intact. Subsequently, embryos were either freshly transferred on day 2 (ZP-intact group only, according to patients’ wishes), or day 5/6, or they were cryopreserved on day 5/6/7 for future embryo transfer cycles for both groups. Main Outcome Measure(s): Rates of good-quality embryos, blastocyst development, morphologically good-quality blastocyst development, and cryopreservation. Result(s): In ZP-free embryos, the inter-blastomere adhesion was not disturbed and the fragmentation was significantly decreased that resulted into significant improvement in all measured parameters compared with the ZP-intact group. Conclusion(s): Artificial ZP removal at the pronuclear stage may prevent excessive fragmentation leading to good-quality blastocysts. Moreover, patients with recurrent ART failure may achieve successful pregnancies.http://www.sciencedirect.com/science/article/pii/S2666334124000928Zona pellucidacytoplasmic fragmentationblastocyst developmenthuman embryoZP-free culture
spellingShingle Keitaro Yumoto, B.Sc.
Toko Shimura, B.Sc.
Minori Kawamoto, M.Sc.
Minako Sugishima, B.Sc.
Yasuyuki Mio, M.D., Ph.D.
Artificial removal of the zona pellucida at the pronuclear stage: an exploratory study to improve embryo fragmentation
F&S Reports
Zona pellucida
cytoplasmic fragmentation
blastocyst development
human embryo
ZP-free culture
title Artificial removal of the zona pellucida at the pronuclear stage: an exploratory study to improve embryo fragmentation
title_full Artificial removal of the zona pellucida at the pronuclear stage: an exploratory study to improve embryo fragmentation
title_fullStr Artificial removal of the zona pellucida at the pronuclear stage: an exploratory study to improve embryo fragmentation
title_full_unstemmed Artificial removal of the zona pellucida at the pronuclear stage: an exploratory study to improve embryo fragmentation
title_short Artificial removal of the zona pellucida at the pronuclear stage: an exploratory study to improve embryo fragmentation
title_sort artificial removal of the zona pellucida at the pronuclear stage an exploratory study to improve embryo fragmentation
topic Zona pellucida
cytoplasmic fragmentation
blastocyst development
human embryo
ZP-free culture
url http://www.sciencedirect.com/science/article/pii/S2666334124000928
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