Fluorochromes (fluorescent chromogens) are the molecules attached to the DNA probe that provide a method for visualization. Fluorophores on the DNA probe will fluoresce (give off) a specific light color with exposure to certain wavelengths of light, which can be viewed only with a fluorescent microscope. When the light hits these molecules, it excites them and causes them to emit a complementary, longer wavelength of light at a lower energy level. The number and pattern of fluorescent signals observed can be used for a quantitative diagnostic evaluation of the breast tumor.