Fig. 1.

Phenotype of cells present in the urothelium of adult mouse bladders. The urothelium has 3 cell layers: basal, intermediate, and superficial. Associated with the basal cell layer are two cell populations: one is TP63⁺, SHH⁺, KRT5⁺, and KRT14⁺ (green-colored cell) and proliferates in response to urothelial injury, and the other cell type is TP63⁺, SHH⁺, KRT5⁺, and KRT14⁻ (mauve-colored cells). Basal cells are the only cells that form hemidesmosomes and express the β₄-integrin receptor. Intermediate cells also have two phenotypes. The majority of cells (yellow colored) are TP63⁺, SHH⁺, and KRT5⁺, whereas a smaller population express TP63 and SSH, but not KRT5 (cyan colored). This latter population of cells also expresses UPKs (which are present in discoidal- and/or fusiform-shaped vesicles; DFVs), and can give rise to superficial cells in response to acute injury. Umbrella cells are UPK⁺ and KRT20⁺ (pale blue colored). They are attached to one another by junctional complexes and their cytoplasm is filled with DFVs.