Homotypic biofilm formation by P. gingivalis wild-type strain and mutants in dTSB. P. gingivalis strains were stained with CFSE (green) and incubated in dTSB for 24 hours. After washing, the biofilms that developed on the coverglasses were observed with a CLSM equipped with a 40× objective. Optical sections were obtained along the z axis at 0.7-μm intervals, and images of the x-y and x-z planes were reconstructed with imaging software, as described in the text. Upper panels indicate z stacks of the x-y sections. Lower panels show x-z sections. The experiment was repeated independently three times with each strain in triplicate. Representative images are shown.