Ultrastructural aspects of human gallbladder epithelial cells in cholelithiasis: production of anionic mucus.

The surface epithelium of 28 gallbladders removed during elective cholecystectomies and pathology collection was studied ultrastructurally. Focusing on 10 of the 28 cases that were diagnosed as cholecystitis, we found that the epithelium displayed numerous apical mucous granules and bulging apical apices. Mucous granule changes included 1) hyperproduction of secretory granules of neutral type containing an electron-dense proteinaceous spherule, similar to that described in other mucus-producing glands of the digestive system, and 2) production of anionic, osmiophilic secretory mucus. Other alterations of the surface epithelial cells included the production of bizarre surface appendages resembling primitive cilia without axoneme and epithelial excrescences.