An allochrome periodic acid-methenamine silver stain for demonstrating mycobacteria in tissue sections.

Nyka9) employed the Gomori-Grocott's chromic acid-methenamine silver method for demonstrating tubercle bacilli in tissue sections after sublimate fixative with added hydrogen peroxide or periodic acid. He described that this procedure could demonstrate mycobacteria that had lost their acidfastness by the usual carbol fuchsin stain. Harada5) also employed the periodic acid-methenamine silver stain for demonstrating mycobacteria including leprosy bacilli in tissue sections after formalin fixation. After many trials, the author recommended the following modification of the periodic acid-methenamine silver stain with added contract trichrome stain of background tissues for selective identification of mycobacteria and pathological changes.