Source:http://linkedlifedata.com/resource/umls/id/C0683225
NCI: The visual appearance of a chromosome when stained and examined under a microscope. Particularly important are visually distinct regions, called light and dark bands, which give each of the chromosomes a unique appearance. This feature allows a person's chromosomes to be studied in a clinical test known as a karyotype, which allows scientists to look for chromosomal alterations. (NHGRI Glossary of Genetic Terms)