Figure 5.

Ultrastructure of interstitial cells. (a) A myofibroblast located in the lamina propria. The cell is identified by filaments (fil), focal densities (fd), membranous attachment plaques (ap), subsurface vacuoles (arrow), mitochondria (m), and prominent rough endoplasmic reticulum (r). Cytoplasmic filaments cohere to a membranous attachment plaque, showing intimate association with its neighboring cell (arrowhead). Magnification ×420,000. (b) Overview of cells in the lamina propria. The left upper corner shows a myofibroblast (mf). Note its stellate morphology with multiple branches. The cell is accompanied by fibroblasts (f). Magnification ×10,500. (c) Two closely associated interstitial cells in the detrusor layer. (d) Higher magnification of (c). Branched interstitial cell shows mitochondria (m), interrupted basal lamina (arrowhead), peripheral filaments (fil), membranous attachment plaques (ap), focal densities (fd), and prominent rough endoplasmic reticulum (r). Numerous tubulovesicular structures (open arrow) were found exclusively in this cell type.