The Structure of Spirochaeta novyi as Revealed by the Electron Microscope12
Journal of Bacteriology
The first observations on the morphology and structure of the spirochetes of relapsing fever with the electron microscope were made over three years ago. Ensuing studies showed (1) that with different methods of preparation, the spirochetes exhibited striking variations in morphology, and (2) that many cells possessed structures, such as flagellalike fibers, huge bulges in the organisms, and large, dense granules either attached to the cell or free in the medium, which had not been described by
... t been described by workers using the ordinary microscope. Also some of the spirochetes were fragmented. The specimens for examination were obtained from the blood of infected rats, since cultures of these organisms on laboratory media are unavailable. The spirochetes were repeatedly washed and centrifuged in an attempt to produce satisfactory preparations, and, as a result, parasites having the morphology considered to be normal on the basis of direct examination and stains of infected blood with the usual illumination were rarely present. In addition, a study of the effect of low temperature on the structure of Spirochaeta novyi indicated that a heavy granulation of the protoplasm resulted from the progressive precipitation of a dark-staining phase. In some cases repeated freezing and thawing produced practically complete precipitation and, finally, fragmentation of the spirochetes (Lofgren and Soule, 1945). It seemed desirable to carry out a more intensive study on the structure of Spirochaeta novyi with the electron microscope. The investigation consisted of three parts: (1) the development of a method for the preparation of specimens, (2) the examination of the normal structure of the spirochetes, and (3) an attempt to reveal more of their structural makeup by fragmentation of the cells. There are no previous reports of electron microscope studies of Spirochaeta novyi; however, the structures of other spirochetes have been observed by several workers. Describing Nichol's strain of Spirochaeta pallida, Morton and Anderson (1942) stated that "the organisms were frequently surrounded by what appeared to be a slime sheath which occasionally formed thin tendrils projecting from the organisms." They also observed granules, lateral buds, and constrictions in the body of the cell. In a note, Wile, Picard, and Kearney (1942) mentioned that flagellalike processes were seen along the body of the organism but not at the ends of the spirochetes obtained from the primary lesions of syphilis. In addition, a continuous envelope surrounded the cells, and a knoblike struc-1 Part of this material was submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the University of Michigan.