Maturation capacity, morphology and morphometric assessments of human immature oocytes after vitrification and in vitro maturation
Introduction: Immature oocytes collected in ART cycles may be cryopreserved further for use in in- vitro maturation (IVM) program. The aim of this study was to determine maturation capacity, morphometric parameters and morphology of human immature oocytes in both fresh IVM (fIVM) and vitrified-IVM (vIVM) oocytes. Materials and Methods: 93 women aged 21-49 year old who underwent controlled ovarian stimulation for ART were included. The immature oocytes (n=203) were divided into two groups: (I) immature oocytes (n=101) that were directly matured in vitro; (II) immature oocytes (n=102) that were first vitrified, then matured in vitro. All oocytes underwent IVM in Ham's F10 supplemented with 0.75 IU LH and 0.75 IU FSH and 40% human follicular fluid (HFF). After 48 h of incubation, the oocyte maturation rates, as well as morphometric assessments and extra and intracytoplasmic morphology evaluation, were assessed using Cornus imaging program and then were compared. Results: Oocyte maturation rates were significantly reduced (p<0.001) when oocytes were vitrified at immature stage followed by IVM (40.4%) in comparison with, fIVM assess (59.4%). Following morphometric assessment, there was no difference in the mean oocyte diameters (µm) between fIVM and vIVM, 156.3±6.8 and 154.07±9.9 respectively. Other parameters of perimeters, egg areas, as well as oocyte and ooplasm volumes were similar in two groups. In addition, more morphologic abnormalities, such as, vacuole, dark oocyte was observed in vIVM oocytes. Conclusion: Because fIVM was more successful than vIVM groups, morphometric parameters cannot be applied as prognosis factor in oocyte maturation outcome in IVM program.