Aqueous solution of cresyl violet--its use in the staining of DNA in fixed mammalian tissue sections

This communication presents observations on the ability of an aqueous solution of cresyl violet to demonstrate DNA in deparaffinised rat tissue sections from which RNA has been extracted selectively with 90% phosphoric acid at 5 degrees C for 40 min. An aqueous solution of cresyl violet was found to be highly unstable and, therefore should be used when freshly prepared. The peak of maximum absorption of stained nuclei has been found to be at 560 nm. Staining of the nuclei following extraction of RNA has been due to the phosphate groups of DNA which is found to be in a native state.