Scanning electron microscopy of chromosomes.

Scanning electron microscopic analysis is an indispensable tool for high-resolution visualization of chromosomes and their ultrastructural details. It allows a three-dimensional structural approach for elucidating higher-order chromatin structure and chromosome architecture. Artificial decondensation under a variety of conditions shows that structural elements of chromosomes are composed of matrix fibers and chromomeres. Currently, chromosome labeling methods include DNA contrasting with platinum blue, silver contrasting of proteins, and immunolabeling with Nanogold. With these techniques, DNA and protein distribution can be determined, and functionally relevant elements (e.g., epigenetic modifications, specific proteins, DNA sequences) can be located to structural elements of chromosomes with, at present, local resolution of approximately 30 nm.