Morphological assessment of oocytes, zygotes and embryos in a human in vitro fertilisation programme.

摘要

During in vitro fertilization treatments embryos are selected for transfer on the basis of their developmental stage and morphology. However, more and more data are published, which demonstrate that morphological features of oocytes and zygotes can be related to the embryo viability. The aim of this study was to correlate morphological characteristics of oocytes and the timing of early embryonic development to the further embryo quality and the outcome of IVF treatments.;During our retrospective study we analysed the data of IVF treatments performed between 2001. October and 2005. February in the Division of Assisted Reproduction, First Department of Obstetrics and Gynaecology, Semmelweis University School of Medicine, Budapest. Assessment of oocyte morphology were included the characteristics of first polar body, the size of perivitelline space and granules or vacuoles occurred in the cytoplasm. During assessment of early embryonic development we observed the timing of the pronuclear membrane breakdown and the first cleavage.;On the basis of our results, we concluded that fragmented first polar body, enlarged perivitelline space, minor granulation of cytoplasm and occurrence of insignificant vacuolisation have no detrimental effect on fertilization and further embryo development. However, large or immature polar body, refractile bodies, dense centrally located granularity, considerable vacuolisation or occurrence of sacculus-like structure in the cytoplasm correlated to lower chance for fertilization and decreased embryo quality. Thus, we do not suggest transferring embryos developed from oocytes with these anomalies.;We suggest performing the assessment of early pronuclear breakdown between 22-25 hours post-insemination. Those embryos which passed pronuclear breakdown by this period have faster development and better morphological quality. Transferring these early developing embryos resulted in a higher pregnancy and implantation rate than those which had intact pronuclei at the assessment of early embryonic development. On the basis of our result, we suggest that assessment of early pronuclear breakdown should be included in the scoring system to select the most viable embryos for transfer.