Abstract
Purpose: Our purpose was to investigate the factorsinfluencing maturation and fertilization of immature oocytes.
Methods: Immature oocytes were obtained from womenundergoing cesarean section. They were cultured in thematuration medium either with or without cumulus cells. Aftermaturation to metaphase II, they were randomly fertilizedby in vitro fertilization (IVF) or intracytoplasmic sperminjection (ICSI).
Results: After incubation for 48 hr, 441 oocytes (42.8%)reached metaphase II. Among them, 56.6% ofcumulus-enclosed oocytes, but only 29.2% of denuded oocytes,reached metaphase II. Of the 289 cumulus-enclosed oocytes,the fertilization rates by IVF and ICSI were 56.3 and 84.1%,respectively (P < 0.01). Of the 152 denuded oocytes, thefertilization rates by IVF and ICSI were 39.5 and 84.5%,respectively (P < 0.01). The cleavage rates, however,were similar.
Conclusions: Cumulus cells are beneficial in the maturationof human oocytes in vitro and that ICSI increases thefertilization rate for the in vitro matured oocytes. Thedevelopmental potential of the fertilized oocytes, however, is similarirrespective of the fertilization method or the presence orabsence of cumulus cells.
Keywords: immature oocytes, in vitro maturation, cumulus cells, fertilization, intracytoplasmic sperm injection
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