Morphological observations on the gallbladder of ground squirrels fed a lithogenic diet

Abstract

Richardson's ground squirrels (Spermophilus richardsonii) of both sexes were fed a 2 per cent cholesterol-enriched rat chow diet for intervals of 1, 2, 10 and 20 weeks. Light microscopy and 3H-thymidine autoradiography revealed an increase in cell proliferation prior to the occurrence of macroscopically visible stones, but in the presence of crystals and microliths. Transmission electron microscopy studies showed that columnar epithelial cells undergo mitosis rather than basal cells and that oedematous cells were extruded from the epithelial sheet. Transmission and scanning electron microscopy studies on gallbladders of animals fed the lithogenic diet for 10 and 20 weeks revealed damaged epithelial cells either singly or in groups. Neighbouring cells often slide under the basal aspects of cells being extruded. Hypertrophy, hyperplasia, Rokitansky-Aschoff sinuses, thickening of the lamina propria around the muscle bundles and inflammatory cells in the lamina propria began to occur about the time macroscopically visible stones were present. The epithelium of the Richardson's ground squirrel gallbladder is damaged more slowly than that of other animal models by a cholesterol-enriched, lithogenic diet and may more accurately reflect changes occurring in human cholecystitis.

Ground squirrel model for cholelithiasis: Role of epithelial glycoproteins

“…MacPherson et al (1987) documented the chronology of experimental cholelithiasis in the Richardson's ground squirrel (Spermophilus richardsonii) with scanning electron microscopy. Further investigation into the ultrastructural events exhibited during the chronological development of gallstones using this model revealed mucus hypersecretion (Pemsingh et al, 1987a), lipid accumulation in the mucosa (Pemsingh et al, 1988) as well as increases in cell proliferation, and occurrence of hyperplasia and Rokitansky-Aschoff sinuses during the 20 week experimental period (Pemsingh et al, 1987b). Smith et al (1987) reviewed the model as reported by MacPherson et al (1987) and indicated its great potential based on the very early occurrence of mucus hypersecretion and the ability to modify this response by varying the cholesterol content of the diet.…”

Mucus hypersecretion in the gallbladder epithelium of ground squirrels fed a lithogenic diet for the induction of cholesterol gallstones

“…Increased cellular proliferation was another feature observed in the response of ground squirrel gallbladder epithelium to a cholesterol-enriched diet. Mitotic and labeling indices of gallbladder epithelium increased during the early phases, independent of and preceding stone formation, distention and inflammatory changes (34).…”

“…Hypersecretion of epithelial mucins prior to cholesterol monohydrate crystal precipitation, a pattern of stone formation similar to man (22), and a concomitant increase in cellular proliferation and eventual mucosal damage as the experimental period progresses (34), have all been shown to be features of the Richardson's ground squirrel-cholesterol model. These similarities indicate the model has great potential in the evaluation of factors which promote or inhibit gallbladder disease and its treatment.…”

Lowering of lipid composition in aorta of guinea pigs by Curcuma domestica

“…Hypercholesterolemia was induced in the animals by giving cholesterol (Sigma Chemical Co., St. Louis, USA) mixed with the rabbit chow pellet (2% cholesterol, w/w, in food pellet) [5]. For each 100 g of ground rabbit chow pellet, 2 g of cholesterol were added and mixed with a little sterile distilled water.…”