Karyotyping under light microscopy is done by:
G banding Ref: Robbins 7/e p170; Also see q no. 29 of May 2007 "The study of chromosomes--kwyotyping--is the basic tool of the cytogeneticist. The usual procedure of producing a chromosome spread is to arrest mitosis in dividing cells in metaphase by the use of mitotic spindle inhibitors (e.g.. colcemid) and then to stain the chromosomes. In a metaphase spread, the individual chromosomes take the form of two chromatids connected at the centromere. A karyotype is a standard arrangement of a photographed or imaged stained metaphase spread in which chromosome pairs are arranged in order of decreasing length. A variety of staining methods that allow identification of each individual chromosome on the basis of a distinctive and reliable pattern of alternating light and dark bands along the length of the chromosome have been developed. The one most commonly employed uses a Giemsa stain and is hence called G banding." - Robbins Pathology 7/e pl70 A karyotype is the number and appearance of chromosomes in the nucleus of a eukaryote cell. The term is also used for the complete set of chromosomes in a species, or an individual organism. Karyotypes describe the number of chromosomes, and what they look like under a light microscope. Attention is paid to their length, the position of the centromeres, any differences between the sex chromosomes, and any other physical characteristics. The preparation and study of karyotypes is pa of cytogenetics. The study of karyotypes is made possible by staining. Usually, a suitable dye, such as Giemsa is applied after cells have been arrested during cell division by a solution of colchicine. The dye stains regions of chromosomes that are rich in the base pairs Adenine (A) and Thymine (T) producing a dark band.
R banding
Q banding
G banding
C banding