The effect of fixatives on staining procedures for lepra bacilli in tissues.

An essential to the study of the histiogenesis of leprosy consists of reliable demonstrations of the bacilli in tissues. In the older days, when celloidin embedding was more widely used, fair results were often seen. Paraffin embedding, however, has almost totally replaced celloidin in common practice, and the problem has become that of determining the conditions of fixation, dehydrating, and staining calculated to produce the best results. In order to determine the ideal fixative, four of the ones commonly employed were tested on biopsy specimens of lepromatous tissues, by varying only the fixative and using the same methods of preparation of blocks and of staining. The fixatives tested were: