Compaction, stainability and methylation of the late replicating X chromosome in mouse female fibroblasts.

In metaphases from female mouse fibroblasts, successive stainings by Giemsa and DAPI and immunolabeling of 5-methylcytosine were performed with or without bromodeoxyuridine pretreatment. It was shown that, compared to all other chromosomes, the late replicating X is the least methylated, the most compacted, and the most intensely stained by DAPI and Giemsa.