Chromosome Banding and Identification Absorption Staining

Chromosome banding is the use of special staining procedures to induce patterns of longitudinal differentiation along chromosomes, in the absence of any structural differentiation (1 ,2 ). Specific chromosomes have characteristic patterns that permit their identification throughout a species and even in related species. Some types of banding, however, draw attention to restricted regions of chromosomes and give indications of the functional properties of those regions: for example, nucleolar organizers (NORs) and kinetochores. Other types of bands show differences in size or staining properties between homologous chromosomes. Thus, although in many cases chromosome banding is used purely or primarily as a means of identifying chromosomes, both normal and abnormal, it can also be used to study chromosomal variation or certain aspects of chromosomal function. In addition, banding is a reflection of certain aspects of chromosome organization that are worthy of study in their own right (2 ,3 ).