Electron microscopic observations of cell wall and cytoplasmic membrane in murine and human leprosy bacilli

The cell wall and the cytoplasmic membrane of Mycobacterium lepraemurium in murine lepromas and M. leprae in human skin lepromas were studied in ultrathin serial sections at the electron microscopic level. The cell wall in M. lepraemurium was composed of three layers: an innermost electron-dense layer, an intermediate electron-transparent zone, and a thin outermost electron-dense layer. The fine structure of the cell wall in M. leprae was slightly different. In general, the cytoplasmic membrane of M. lepraemurium and M. leprae seemed to have a similar structure.