Various morphological abnormalities of human oocytes were reported to detrimentally affect embryo development. We observed development of frozen thawed embryos derived from oocytes with normal or abnormal morphological features to the blastocyst stage. Cytoplasmic abnormalities of the oocytes were found to negatively affect cryosurvival potential of the embryos.

Inclusion Criteria:

• Human embryos derived from morphologically normal or abnormal mature oocytes that fertilized normally by microinjection procedure.
• Embryos were obtained from couples who refused to freeze their supernumerary embryos after fresh embryo transfer in an assisted reproduction treatment cycle.

Exclusion Criteria:

• Embryos obtained after microinjection to immature oocytes taht were in vitro matured in culture.
• Embryos obtained from abnormally fertilized zygotes.