Hoechst stain
(Redirected from Hoechst 33342)
Transmission image of HeLa cells, with overlay of Hoechst 33258 staining (blue). The leftmost cell is in the anaphase stage of mitosis; its chromosomes fluoresce brightly because they contain highly concentrated DNA.
The Hoechst stains are part of a family of fluorescent stains for labelling DNA in fluorescence microscopy. Two of these closely related bis-benzimides are commonly used: Hoechst 33258 and Hoechst 33342.
Both dyes are excited by ultraviolet light at around 350 nm, and both emit blue/cyan fluorescence light around an emission maximum at 461 nm. The Hoechst stains may be used on live or fixed cells, and are often used as a substitute for another nucleic acid stain, DAPI.
Because the Hoechst stains bind to DNA, they can disrupt DNA replication during cell division. Consequently they are potentially mutagenic and carcinogenic. Care should be taken in their handling and disposal.
Hoechst 33258
Hoechst 33342