Junctional pattern in the squamous metaplasia of the female trigone. A freeze-fracture study

The junctional pattern of squamous metaplasia in the female trigone was studied by the freeze-fracture technique. Desmosomes were observed in all epithelial layers and varied in complexity from the basal to the superficial layers. Gap junctions were observed in the lower and upper epithelial layers. Tight junctions were detected occasionally in the superficial layer only, which appeared as maculae and did not form zonulae occludens. These data support previous suggestions that the squamous metaplastic epithelium is not waterproof and may interfere with the contraction-expansion mechanism of the bladder.