Human embryos derived from in vitro and in vivo matured oocytes: Analysis for chromosomal abnormalities and nuclear morphology

Purpose: To determine whether embryos resulting from oocytes matured in vit ro have a higher incidence of nuclear and/or genetic abnormalities compared to embryos resulting from oocytes matured in vivo. Methods: Fluorescence in situ hybridization analysis Sor chromosomes X, Y, and 18 was used to compare the rates of aneuploidy, mosaicism, and nuclear abnormalities in embryos derived from oocytes that were prophase I at aspir ation (immature group) to that observed in embryos resulting from oocytes t hat were metaphase I or II at aspiration (mature group). Results: Based oil nuclear morphology: significantly more embryos in the ma ture group (23%) were classified as normal compared to embryos in the immat ure group (3%). No difference was found in the rate of aneuploidy or in rit e incidence of mosaicism involving these chromosomes. Conclusions: These findings suggest that few embryos derived from prophase I oocytes collected following ovarian stimulation are morphologically norma l.