Ultraviolet absorbing dyes as histochemical reagents

Three biochemical methods depending on measurement of absorption in the ultraviolet range were successfuly adapted to histochemical techniques to be used in conjunction with ultraviolet microscopy. They included cetyl pyridinium chloride (max. = ca. 260 nm) as a stain for acid mucopolysaccharides; picryl sulfonic acid (max. = ca. 340 nm) as a stain for proteins, particularly amino groups; and fluorescein mercuric acetate (max. = 293 nm) as a stain for protein bound sulfhydryl and disulfide groups. The general possibilities of this approach was discussed.