Editing Optical microscope (section)

===Fluorescence microscopy===
Modern biological microscopy depends heavily on the development of [[fluorescent]] [[Hybridization probe|probe]]s for specific structures within a cell. In contrast to normal transilluminated light microscopy, in [[fluorescence microscopy]] the sample is illuminated through the objective lens with a narrow set of wavelengths of light. This light interacts with fluorophores in the sample which then emit light of a longer [[wavelength]]. It is this emitted light which makes up the image.{{cn|date=December 2024}}

Since the mid-20th century chemical fluorescent stains, such as [[DAPI]] which binds to [[DNA]], have been used to label specific structures within the cell. More recent developments include [[immunofluorescence]], which uses fluorescently labelled [[antibodies]] to recognise specific proteins within a sample, and fluorescent proteins like [[Green fluorescent protein|GFP]] which a live cell can [[gene expression|express]] making it fluorescent.{{cn|date=December 2024}}