Electron Microscopic Observations on the Cholesterosis of the Gallbladder, with Special Reference to its Pathogenesis

Abstract

Eight gallbladders with cholesterosis were investigated with light and electron microscopes, and at the same time the specimens were treated with digitonin containing fixatives to trace the transportation of free cholesterol at the ultrastructural level.
Cholesterol solubilized in the gallbladder bile is absorbed into the epithelial cells without involving any ultrastructural changes of the apical cell membranes, possibly by diffusion. The free cholesterol entered into the epithelial cells is thought to have the following three fates: 1) Some part of it is taken into lysosomes and is digested there. 2) Some part of it is taken into endoplasmic reticulum systems and is esterified there to become lipid droplets. 3) The rest is excreted from the cell through the lateral and the basal cell membranes without receiving any metabolic changes.
Lipid droplets synthesized in the epithelial cells are excreted from the cells and are phagocytized by macrophages. It is also imagined that macrophages may have the ability to esterify the free cholesterol.
In the case when lymph vessels are obstructed for some reason, the lymph vessels become to be filled with macrophages containing numerous lipid droplets. Consequently, destruction of the lymph vessels occurs and the macrophages begin to deposit in the lamina propria because of being unable to be carried away through the lymph vessels. Therefore, the cholesterosis of the gallbladder are considered to be originated.