ELECTRON MICROSCOPY OF LEPTOSPIRES. I. ANATOMICAL FEATURES OF LEPTOSPIRA POMONA.

Ritchie, A. E. (National Animal Disease Laboratory, Ames, Iowa), and Herman C. Ellinghausen. Electron microscopy of leptospires. I. Anatomical features of Leptospira pomona. J. Bacteriol. 89:223-233. 1965.-Anatomical features of Leptospira pomona are described. Most cells in the logarithmic phase of growth, when examined in whole cell "negative-stained" preparations, display a homogeneous finely granular protoplasmic cylinder. Some cells contain discrete or complex lamellar structures. The cell termini are attached to the protoplasmic cylinder by a membrane system. Each organism appears to have two independent axial filaments originating from opposite ends of the cell. The axial filaments are composed of a closely knit bundle of some 12 to 15 individual strands. A simple model suggesting a locomotory function for the axial filaments is presented. A superficial callouslike mass is occasionally observed in the cell's terminal region. The enveloping sheath is similar to the cytoplasmic membrane; both are triple-layered and ca. 50 A thick. The sheath preferentially forms blebs at the cell termini and midway along the protoplasmic cylinder. Septal-wall formation occurs at the mid region of the cell, and it is concluded that simple transverse binary fission is the predominant mode of reproduction.