Three-dimensional structure of the cytoskeleton in Trichomonas vaginalis revealed new features.

The flagellated protozoan Trichomonas vaginalis has been widely studied owing to its medical significance and unique structure. The complicated three-dimensional (3D) structure of the cellular components of T. vaginalis was reconstructed from serial sections to enable observation of the spatial features of the whole cell. Electron tomography was used to examine the detailed structure of the cellular organelles. Tomographic reconstruction showed the mastigont system and the parabasal filament of T. vaginalis in detail. The last thin filament (Pf3) was located close to the adjacent filament, and the two filaments appeared to be vertically parallel in the cross-sectional view. It is likely that Pf3 cannot be distinguished from the adjacent filament in 2D images obtained from transmission electron microscopy. Our 3D reconstruction of T. vaginalis revealed the presence of an additional striated fiber, and 3D reconstruction by electron tomography showed twisting of the split parabasal filament.