A scanning electron-microscopic study of the muscle layer of the canine gallbladder

A connective tissue digestion and removal technique utilizing collagenase and hyaluronidase incubation followed by treatment with 8 N hydrochloric acid successfully revealed the muscular components within the gallbladder wall of the dog, allowing three-dimensional visualization with the scanning electron microscope. The muscle adjacent to the serosa appeared as a homogeneous layer with few discontinuities. In contrast to this were the more superficial muscle layers which were arranged as a meshwork of interlacing smooth muscle bundles of various size, the interstices of which were filled with cellular connective tissue. These gaps in the muscle layer varied in size, becoming larger as the muscle bundles tapered out just below the mucosal aspect of the gallbladder wall.