Scanning electron microscopy (SEM) is one of the indispensable tools for high-resolution visualization of chromosomes and their ultrastructure.SEM can be applied to high-accuracy three-dimensional imaging for studying chromosome architecture and higher-order chromatin structure.With improvement in artificial decondensation and chromosome labeling techniques,structural elements of chromosome,including DNA and protein distribution,can be detected.Functional elements (e.g.DNA sequences,specific proteins,epigenetic modifications) also can be located.Techniques in electron microscopy using ionic liquid will have to open a new view of studying chromosomes with microscopy.