Effect of modified single cell fixation method on cell-nuclear areas and fluorescence in-situ hybridization signals.

ABSTRACT

BACKGROUND: Fluorescence in situ hybridization (FISH) is an irreplaceable method in pre-implantation genetic diagnosis. We explored the effects of a modified single cell fixation method on the cell-nuclear area and FISH signal. METHODS: From January 2006 to March 2008, the blastomeres with marked nuclei from D3 embryos were selected. Cells were fixed with three different methods. The effects of the three methods on the cell-nuclear areas and FISH signals were then analyzed. RESULTS: The cell fixation rate was higher in conventional (Group B, 94.85%) and modified (Group C, 95.79%) Tween-20/HCl + methanol/glacial acetic acid methods than in the methanol/glacial acetic acid method (Group A, 86.73%) with p < 0.05. The complete signal rates in group A, B, and C were 95.3%, 93.5%, and 93.4%, respectively, with p > 0.05. The mean cell-nuclear areas in groups A, B, and C were 55.3, 46.2, and 49.5 microm3, respectively, with p < 0.05 in group A compared with group B or C, but with p > 0.05 between Group B and C. There was no significant difference in signal overlap and splitting rates between the three groups. CONCLUSIONS: Modified Tween-20/HCl + methanol/glacial acetic acid method fails to increase FISH signal overlap and splitting rates. It is simple and its fixation time is short. It can be widely used in clinical practice.