UPEC IBC Pathogenic Pathway Observed in the Murine Cystitis ModelThe bladder urothelium (A) is a pseudostratified transitional epithelium lined by large facet cells. These cells have an apical asymmetric unit membrane containing uroplakins that help form the impermeable bladder barrier and also serve as receptors for UPEC. Bacteria introduced into the bladder adhere to the bladder surface via type 1 pili (B). Upon attachment, bacteria are able to invade (C) and replicate (D) within the facet cell cytoplasm. UPEC form large biofilm-like IBCs within these cells (E). Ultimately the bacteria flux out of their intracellular niche (G), some adopting a filamentous morphology; they then adhere to other host cells and re-enter the infectious cycle. During this process, infected urothelial cells are sloughed into the urine (F) and neutrophils are recruited to the site of infection.