The outcome of ICSI of immature MI oocytes and rescued in vitro matured MII oocytes

D. Strassburger, S. Friedler, A. Raziel, E. Kasterstein, M. Schachter, R. Ron-El

Research output: Contribution to journalArticlepeer-review

65 Scopus citations


Background: The use of immature oocytes is limited to cases where these are the only available oocytes, and they are usually only microinjected with sperm after having undergone maturation in vitro. This study compares the outcome of injection of sperm into metaphase I oocytes immediately after their denudation (MI) performed 2 h after their retrieval, with the outcome of injection of sperm into rescued in vitro matured metaphase II (IVM MII) oocytes after their short incubation in routine laboratory conditions. Methods: ICSI was performed on MI oocytes, rescued IVM MII oocytes and on MI oocytes that were incubated but failed to extrude their first polar body (arrested IVM MI). Fertilization and cleavage rates were compared with those achieved in mature metaphase II oocytes (MII). Results: ICSI of MI oocytes showed impaired performance compared with ICSI of rescued IVM MII oocytes and MII oocytes, in terms of oocyte degeneration rate (11 versus 6 versus 4%; P < 0.0001), fertilization rate (28 versus 44 versus 68%; P < 0.0001) and multipronucleated fertilization (10 versus 4 versus 4%; P < 0.01). The cleavage rate was lower in rescued IVM MII oocytes compared with MII oocytes (86 versus 95%; P < 0.01). Arrested IVM MI oocytes showed similar results to those of MI oocytes but had a lower cleavage rate (72 versus 96%; P < 0.01). Conclusions: The injection of rescued IVM MII oocytes is preferred to the injection of MI oocytes.

Original languageEnglish
Pages (from-to)1587-1590
Number of pages4
JournalHuman Reproduction
Issue number7
StatePublished - 1 Jan 2004
Externally publishedYes


  • Fertilization
  • ICSI
  • In vitro maturation
  • MI oocytes

ASJC Scopus subject areas

  • Reproductive Medicine
  • Obstetrics and Gynecology


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