Analysis of mucus secretion in the gallbladder of the Richardson's ground squirrel fed a lithogenic diet

The Richardson's ground squirrel has proven to be a reliable model for the study of mucus hypersécrétion and stone formation when fed a lithogenic diet. Male and female ground squirrels were divided into two groups. The control groups were fed a commercial rat-chow diet while the experimental groups were fed a 2% cholesterol-enriched rat chow diet. Sample intervals of 6, 12,18. 24 hours, 3.5,7 days and 2,3,10 and 20 weeks were used. Sections were stained with either HID-AB pH 2.5 or KOH-AB pH 1.0-PAPS for light microscope histochemistry. For TEM Histochemistry, tissue was stained with Low Iron Diamine or High Iron Diamine. The gallbladder epithelium of control animals secreted both sialylated and sulphated mucins. In the experimental animals, the majority of cells secreted sulphated mucins. This pattern varies from that typically seen in other regions of the gastrointestinal tract where sialomucins predominate during pathologic processes.