RESUMO
The morphological features of M. leprae, M. leprae murium, M.tuberculosis, M. smegmatis, M.phlei, and of the vole bacillus were compared by electron microscopy. A cell wall and nuclear structures were observed in the different species, and their characteristics were defined. Changes in the morphology of M.leprae murium as a result of exposure in vitro to saponified fractions of moogrol, to oleic acid, as well as to boiling in 0.85 per cent salinesolution, to strong bases and to formaldehyde, are described. Te morphologic pattern of M. leprae and of M. leprae murium, as revealed by electron micrographs, is in general respects different from that of the cultivable mycobacteria. On the other hand, these two leprosy strains slosely resemble each other.