Journal of Assisted Reproduction and Genetics

, Volume 24, Issue 10, pp 471–475 | Cite as

Chemical zona pellucida thinning with acidified Tyrode’s solution: comparison between partial and circumferential techniques

  • Kohji YanoEmail author
  • Chieko Yano
  • Toshiko Kubo
  • Ikuko Ôhashi
  • Nagamasa Maeda
  • Takao  Fukaya



To compare effectiveness of two different chemical zona thinning techniques.


We studied 163 patients who had experienced IVF or ICSI failures in two or more cycles. Patients were assigned to one of three groups: zona intact (n = 72), partial thinning (n = 59), or circumferential thinning (n = 73). Before transfer, the zonae pellucidae of embryos were thinned partially or circumferentially using acidified Tyrode’s solution.


Implantation rates were 8.9% in the intact zona group, 17.6% in the partial thinning group, and 11.9% in the circumferential thinning group: respective clinical pregnancy rates were 16.7% (12/72), 32.2% (19/59), and 27.4% (20/73). Both rates were significantly higher in the partial thinning group than the intact zona group. For circumferential thinning versus zona intact groups, differences fell short of significance.


Following embryo transfer failure, partial thinning would be recommended over circumferential thinning for successful assisted hatching.


Assisted hatching Acidified Tyrode’s solution Partial zona thinning Circumferential zona thinning 


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Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  • Kohji Yano
    • 1
    Email author
  • Chieko Yano
    • 1
  • Toshiko Kubo
    • 1
  • Ikuko Ôhashi
    • 1
  • Nagamasa Maeda
    • 2
  • Takao  Fukaya
    • 2
  1. 1.IVF CenterYano Maternity ClinicMatsuyamaJapan
  2. 2.Department of Aging and Reproductive MedicineKochi Medical SchoolKochiJapan

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