抄録
The fine structure of Borrelia duttonii has been studied by observing sections fixed with osmium tetroxide and treated with uranyl acetate. Both the cell body and the bundle of fibrils twisting around the cell are inclusively enveloped by the slime-like layer. In addition to the envelope the surface structure of the cell body appears to consist of two components: cell wall and cytoplasmic membrane. The cell wall appears to be composed of an outer thin layer and of an inner broad layer, and the cytoplasmic membrane appears as a dense thin layer. At the time of cell division the cytoplasmic membrane, together with the cell wall, invaginates into the cytoplasm to form the septum.
The cytoplasm showing granular texture contains the nuclear regions which are situated at the central area along the longitudinal axis of the cell and have a lower average density than the cytoplasm. The nuclear regions are occupied by a fine network with random distribution of the nuclear fibrils. The appearance of the nuclear region is thought to be similar to that of the bacterial nuclei observed in the sections.
A membranous aggregate is seen near the periphery of the cytoplasm. A large laminated organelle also is shown in the nuclear region and its appearance closely resembles the membranous organelle observed in bacterial cells.
