Figure 4.

FISH analysis of the number of total X-chromosomes as well as the number of inactive Xs. The total number of X-chromosomes in HDF cells at passage 10 was detected by DNA FISH analysis of the centromeric region of X chromosome (green) and the number of inactive X chromosomes by XIST RNA FISH assay (red). Note that the double signals for XIST RNA are indicative of the two inactive Xs, which can be observed in cell nucleus with either quadruple-signals for X chromosome (A) or triple signals for X chromosome (B). Cell nucleus was counterstained with DAPI (blue).