Abstract: In order to study the ultrastructure of T.pallidum and damaging effect of it to host cell surface,the epithelial cells of 13 patients with condyloma latum were frozen and cut,and the epithelial cell surface was examined with the scanning electron microscope(SEM). Under SEM, each T.pallidum had 7 to 12 spirals. The projection wave length of the T.pallidum was 0.6 to 1.2μm, and the amplitude was 0.15 to 0.3μm. The length of two terminal axes of T.pallidum was 7.0 to 13.0μm, and the projection body axis was 8.3 to 22.0μm in length, while the proportion of the two terminal axes and body axis was 1:1.2 to 1.9. The diameter of transverse section of T.pallidum was about 0.16μm. A large amount of T.pallidum were seen adhered to one host cell surface after freezing and cutting treatment. On one image of the SEM,more than 20 T.pallidum were seen adhering to the host cell mambrane.On the host cell membrane adhered with T.pallidum, holes of different sizes could be seen. The results suggest that after adhering of T.pallidum to the host cell surface, the host cell membrane is damaged, and causes a series of pathological changes of tissue and cells.

Key words: Treponema pallidum, Scanning electron microscope, Adhere, Host cell