Treponema pallidum’s structure is similar to that of other spirochaetes: it is helical, a protoplasmic cylinder twisted into 8–12 whorls; 3 periplasmic flagella extend from the ends of the cell. Studies of the morphology of pale treponema conducted using electron microscopy showed that the central structure of the Treponema pallidum cell is a spirally twisted protoplasmic cylinder. The protoplasmic cylinder is surrounded on the outside by a cytoplasmic membrane and a thin cell wall tightly adjacent to it, the basis of which is peptidoglycan. In addition, pale treponema has axial fibrils that wrap tightly around the protoplasmic cylinder. The bacterium has an outer membrane. The outer membrane encloses the protoplasmic cylinder and fibrils.
Reproduction of the Treponema pallidum occurs by simple division; the life cycle is about 30–33 hours. When adverse conditions occur, it forms cysts, allowing the infection to persist for a long time (Peeling et al. 2). Treponema pallidum is an obligate anaerobe; that is, it cannot exist in an air environment containing oxygen. Therefore, it is not possible to cultivate these bacteria on ordinary nutrient media.
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