Ultrastructural aspects of human cystic duct epithelium as a result of cholelithiasis and cholesterolosis.
Although there is a large body of data on the gallbladder and the importance of the cystic duct in surgical procedures, there is insufficient data regarding the morphology of the human cystic duct. In the present study, transmission electron microscopic (TEM) and scanning electron microscopic (SEM) survey of several surgical and autopsy cystic ducts in cholelithiasis and cholesterolosis is reported. In cholelithiasis, similar to gallbladder epithelium, the cystic duct epithelial cells display minor-to-severe alterations of the epithelial surface accompanied by variable erosion of the epithelium. Areas of intact surface epithelium demonstrate microvilli-covered cells coated by a rich glycocalyx and mucous production. In other areas, apical excrescences are associated with mucus hyperproduction and secretory events. Lipoid bodies are also present in many cells and especially in many of the cells' subliminal apical areas. In cholesterolosis, mucous secretory granules appear dilated, fatty deposits are infrequent, and peculiar intracellular cholesterol deposits can be detected in the apical and subapical region of cells and around condensed mitochondria. Following elective cholecystectomies, predominantly in association with cholelithiasis, eroded areas were detected; therefore, it appears that the action of intraluminal calculi may be a principal causative factor in discrete epithelial erosions of the cystic duct. Intraluminal calculi/ debris, along with the alteration of mucus, cell sloughing, and a decreased pool of bile acids and motility may participate in the gallstone nucleation process. The peculiar cholesterol inclusions may also play a role in that nucleating process.