Chromosomes are deep compression of genetic material with hereditary properties within the cell to form aggregates, easily stained by alkaline dyes into dark colors, so called chromosomes (chromatin), chromosomes and chromatin is the same material in the interphase of cell division and the division of the different morphology of the manifestation of the different phases only. Chromosomes appear in anaphase, chromatin appears in interphase, filamentous, its essence are deoxyribonucleic acid (DNA) and a combination of proteins (i.e., nucleoproteins composed of), unevenly distributed in the cell nucleus, is the main carrier of genetic information (genes).

Many dyes have varying degrees of affinity for DNA and can therefore be used as chromosome stains. In the routine staining of chromosomes, better staining results can generally be obtained with Giemsa, lichen red, Folgen, and carbolic acid compound red. Sulfur cordial staining solution can be used for chromosome staining of oral mucosa, urine, amniotic fluid, chorionic villus cells and artificially cultured cells and other samples, especially for the staining of sex chromatin which is difficult to color; sulfur cordial staining can also be used for the staining of mast cells, the heterochromatic material is purplish red, and the other is blue.