Fluorescein diacetate (FDA) is a non-fluorescent, lipophilic compound that is widely used in Histology to assess cell viability. It is a derivative of fluorescein, a fluorescent dye. When FDA enters a living cell, it is hydrolyzed by intracellular esterases, producing a fluorescent compound called fluorescein. This conversion makes FDA an effective tool for distinguishing between live and dead cells.
