Objective: To improve the fluorescence in situ hybridization (FISH) chromosomal analysis of human oocytes and first polar bodies.
Design: In situ chromosomal identification on isolated cells, with combinations of centromeric (or locus-specific) probes and whole-chromosome painting probes for chromosomes 9, 13, 16, 18, 21, and X.
Setting: Montpellier University Hospital.
Patient(s): Women participating in an IVF program.
Intervention(s): Fifty-four in vitro unfertilized oocytes were fixed on slides, and simple or double FISH labeling procedures were performed on preparations.
Main outcome measure(s): Simultaneous in situ visualization of specific domains and chromosome arms of each targeted chromosome.
Result(s): Eight chromosomal abnormalities were identified, including two hyperhaploidies, three cases of extra single chromatid, and three cases of balanced separation of sister chromatids. Also, the double-labeling procedure allowed the avoidance of five interpretation errors, owing to additional artefactual signals.
Conclusion(s): By ensuring precise identification of both chromosomes and single chromatids, the FISH double-labeling procedure limits the risk of erroneous interpretation and allows a more accurate cytogenetic analysis of human oocytes.