Figure 3.

Internalization of type 1-piliated UPEC by superficial facet cells. (A–F) Transmission EM shows the AUM of mouse superficial facet cells in various stages of enveloping adherent type 1-piliated UPEC. (F and G) High-resolution freeze-fracture/deep-etch EM also reveals type 1-piliated E. coli (yellow) seemingly being enveloped by facet cells (brown; the AUM and extracellular milieu are colored blue). The cytoplasmic face of three uroplakin plaques, separated by smooth interplaque regions, can be seen in the host membrane that is partially enveloping the bacterium in G. All images were obtained by using C57BL/6 mouse bladders recovered about 1 h after infection with UPEC. [Bars = 1 μm (A and B) and 0.5 μm (C–G).]