ABSTRACT
Modern cytogenetics was born when a series of technical innovations permit accumulation of cells in metaphase by means of colchicine, the use of hypotonic shock and fixation. A great diversity exists in the processes and in the patterns; nevertheless, all chromosome-banding techniques evidence the heterogeneity of chromosome organization. The modern age of chromosome banding began in 1968 when Caspersson and collaborators published their article describing the use of the quinacrine to induce a characteristic and reproducible banding pattern. The modern banding techniques, that intend to understand the underlying mechanisms of chromosome banding, have prompted an extensive investigation in the field of chromosome organization. The development of the modern cytogenetics of vertebrates has been dominated by spectacular results obtained in mammals. The development of unconventional cytogenetic techniques such as in situ treatment with restriction enzymes, capable of digesting the DNA of fixed chromosomes revealing enriched regions in tagged sites, permitted the induction of different types of banding in mammals.
