3-DIMENSIONAL ARRANGEMENT OF COLLAGEN AND ELASTIN FIBERS IN THE HUMANURINARY-BLADDER - A SCANNING ELECTRON-MICROSCOPIC STUDY

To clarify the arrangements of collagen and elastin fibers of the urin ary bladder, we examined 9 human (male, aged 42 to 72) urinary bladder s by scanning electron microscopy with chemical digestion methods. The mucosal layer was divided into 3 portions according to the collagen a rrangement: the superficial portion interwoven densely by collagen fib rils, the middle portion layered by flat bundles of collagen fibrils a nd the deep portion made of a loose network of twisted collagen bundle s. In the muscular layer, the smooth muscle fascicles were firmly cove red with collagen sheets, while each muscle cell in a fascicle was acc ommodated by a thin sheath of collagen fibrils. The serosal layer cons ists of wavy collagen bundles piled up in a sheet, which was intercala ted by clusters of adipose cells. Elastic fibers were, on the other ha nd, sparse throughout the bladder wall, except for denser networks aro und the blood vessels and muscle fascicles and beneath the peritoneal mesothelium. The arrangements of these components were discussed in re lation to the mechanical function and compliance of the urinary bladde r.