The morphology and composition of cholesterol, protein, and bilirubin deposits in dried human bile: cathodoluminescence and backscattered electron imaging.

This work is the first to deal with the application of color cathodoluminescence scanning electron microscopy (CCL SEM) and a novel version of combined imaging with backscattered electrons (CCL + BSE SEM) for the study of the composition of bile and its precipitation mechanisms. The present study demonstrates cholesterol, protein, and bilirubin distribution in deposits of normal and abnormal human bile after solution evaporation to full dryness. Qualitative CCL SEM analysis showed that dried bile remnants include different proportions of the above components. Three types of deposits were observed: Arborescent crystals, typical cholesterol crystals, and amorphous bilirubin particles. The selection of crystalline or amorphous precipitate phases is determined by the dehydration/concentration process. The findings may explain key features in lithogenesis.