FIG. 4.

Invasion of TERT-2 cells by F. nucleatum or S. cristatus. F. nucleatum readily invaded TERT-2 cells (A and B), although blebbing of the fusobacterial membrane was observed for the majority of the bacteria (A, B, E, and F). There was evidence of intercellular migration by F. nucleatum (C). S. cristatus was rarely observed to adhere directly to epithelial cells; attachment occurred via polar tufts of fibrils (D). In coincubation experiments, invading F. nucleatum bacteria were observed with attached S. cristatus (E and F). Bars represent 1 μm.