Fast multicolor primed in situ protocol for chromosome identification in isolated cells may be used for human oocytes and polar bodies

Abstract

Objective To present and evaluate the use of a new ultra-fast multicolor primed in situ (PRINS) procedure for karyotyping human oocytes and first polar bodies. Design In situ chromosomal identification on isolated cells, using combinations of specific primers for chromosomes 1, 7, 9, 16, and 18 and fluorescent nucleotides. Setting Sixteen unfertilized oocytes were obtained from women participating in an IVF program. Patient(s) Five patients undergoing an IVF-ET. Intervention(s) In vitro unfertilized oocytes were fixed on slides, and sequential PRINS reactions were performed on each preparation. Main outcome measure(s) Ultrarapid in situ identification of three or four chromosomes on oocyte and polar body chromosome spreads. Result(s) On the basis of the direct in situ mixing of the colors of fluorochromes (FITC, TRITC, Cascade Blue) that were incorporated in sequential PRINS reactions, this method allows rapid and efficient labeling of three or four individual chromosomes. Each PRINS reaction consists of a unique 4- to 6-minute step for both in situ annealing and elongation. The procedure can be combined with fluorescence in situ hybridization (FISH) reactions. Conclusion(s) By simplifying the multicolor PRINS procedure, this new protocol should facilitate the use and adaptation of PRINS to chromosome screening. This approach could be used in parallel or in combination with FISH for efficient aneuploidy assessment on isolated cells.