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Ibukun Okanlawon: Blastocyst Development After Overnight IVM of MI Oocytes
Ibukun Okanlawon/LinkedIn
May 4, 2026, 11:37

Ibukun Okanlawon: Blastocyst Development After Overnight IVM of MI Oocytes

Ibukun Okanlawon, Clinical Embryologist at Havilland Fertility Clinic, shared a post on LinkedIn:

“In my previous work with GV oocytes, I’ve shared outcomes where overnight in vitro maturation (IVM) resulted in successful blastocyst development, including a euploid embryo.

In those cases, I had little concern about oocyte aging, as GV oocytes still need to progress through MI before reaching MII. The time in culture is largely spent reaching maturity, not sitting in it.

However, carrying out IVM on MI oocytes raised a different question for me. Their transition to MII can occur at any point during culture, making the exact timing of maturity unknown (without time-lapse technology).

What if an MI oocyte reaches MII much earlier than we detect, and then remains at MII for several hours before ICSI?

Could this lead to oocyte aging and impact outcomes: fertilisation, blastocyst development, aneuploidy risk, or implantation potential?

Case 1 (images attached):

  • 6 MI oocytes retrieved
  • No IVM at 3.5 hours post-denudation
  • Cultured overnight
  • At ~19 hours post-denudation, all 6 reached MII
  • All 6 injected → all cleaved (Day 1)
  • Day 5: 2 expanded blastocysts
  • Day 6: 3 expanded blastocysts
  • Total: 5 blastocysts cryopreserved (quality: fair and poor)

Case 2:

  • 3 MI oocytes retrieved
  • No maturation at 4 hours post-denudation
  • Cultured overnight
  • At ~22 hours post-denudation, 2 reached MII
  • All 3 injected (2MII, 1MI)
  • Day 1: 1 (0PN), 1 (2PN), 1 cleaving embryo
  • Day 5: 1 blastocyst (grade 4BC)

It would have been interesting to biopsy these embryos and see what the PGT results showed, as well as the implantation outcomes following FET.”

Ibukun Okanlawon: Blastocyst Development After Overnight IVM of MI Oocytes

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ART Blastocyst development cryopreservation Euploid Embryo fertilisation Fertility Fertility News FET frozen embryo transfer GV oocytes health Ibukun Okanlawon ICSI implantation In vitro maturation IVF IVM OBGYN PGT reproductive health Reproductive Medicine Women’s Health
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