Figure 2.

Type 1 pilus-mediated bacterial attachment to the bladder epithelium. After inoculation of C57BL/6 mice with type 1-piliated UPEC, numerous bacteria (yellow) can be found attached to the luminal surface of the bladder (blue) as detected by scanning EM (A) and high-resolution freeze-dry/deep-etch EM (B). Type 1 pili mediating bacterial attachment were resolved with the high-resolution technique. The scalloped appearance of the bladder surface is attributable to the presence of the uroplakin plaques (≈0.5 μm in diameter). [Bars = 3 μm (A) and 0.5 μm (B).]