Stages in Gallstone Formation

It is clear that gallstone formation is a complex process involving several stages and that the process can be influenced at several points. It is convenient to consider four major stages, which are more or less interdependent and overlapping but which may simplify consideration of experimentally induced cholelithiasis. 

During this stage, the stone grows from micro- to macroscopic size by the deposition of the major stone constituents. For cholesterol stones, at least, this appears to require a bile that is supersaturated with respect to cholesterol. The capacity of bile to hold cholesterol in solution varies from species to species (11), and this accounts for the difficulty in producing cholesterol gallstones in some species and the relative ease with which they can be produced in others. 

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