Preincubation of human oocytes may improve fertilization and embryo quality after intracytoplasmic sperm injection

Author： Rienzi L Ubaldi F Anniballo R Cerulo G Greco E

ISSN： 1460-2350

Source： Human Reproduction, Vol.13, Iss.4, 1998-04, pp. : 1014-1019

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Abstract

The aim of this study was to examine the relationship between different preincubation periods of oocytes and the outcome of intracytoplasmic sperm injection (ICSI). We analysed retrospectively 95 ICSI treatment cycles performed to alleviate severe male-factor infertility. Oocyte collection was performed 36 h after human chorionic gonadotrophin administration. The cumulus-corona-oocyte complexes obtained were incubated until the moment of ICSI. Fertilization, embryo development and implantation rates were analysed in four groups, which were divided according to the time lapse between oocyte retrieval and ICSI: group I, 3 h (18 cycles); group II, >3-6 h (52 cycles); group III, >6-9 h (14 cycles); and group IV, >9-12 h (11 cycles). Immediately before ICSI the cumulus and corona cells were removed from the oocytes. A total of 723 metaphase II oocytes were injected: 126 from group I, 380 from group II, 126 from group III and 91 from group IV. The fertilization rates obtained were 52.3, 66.8, 65.1 and 69.2% respectively [P < 0.05="" (using="" the="">² test) between group I and groups II, III and IV]. Cleavage rates were similar in all groups (68.1, 69.7, 79.2 and 79.3% respectively), but the proportion of good quality embryos (20% fragmentation) was significantly lower (P < 0.05)="" in="" group="" i="" (24.2%)="" compared="" with="" groups="" ii="" (39.8%)="" and="" iv="" (39.6%).="" however,="" no="" statistically="" significant="" differences="" were="" observed="" between="" the="" four="" groups="" with="" regard="" to="" implantation="" rates="" (11.7,="" 13.2,="" 10.4="" and="" 20.4%="" respectively).="" the="" results="" suggest="" that="" a="" preincubation="" period="" between="" oocyte="" retrieval="" and="" icsi="" can="" improve="" the="" fertilization="" rate="" and="" embryo="" quality.="" this="" period="" might="" be="" necessary="" for="" some="" oocytes="" to="" reach="" full="" cytoplasmic="" maturity,="" leading="" to="" a="" higher="" activation="" rate="" upon=""> Keywords:assisted reproduction/fertilization/ICSI/microinjection/oocyte maturity