Lommie, Cholesterol, the major component of most gallstones, is highly insoluble in water, and biliary cholesterol is solubilized in bile salt-phospholipid micelles and phospholipid vesi¬cles. By incorporation into these 2 forms, the cholesterol-carrying capacity of bile is greatly enhanced. Bile salt micelles are aggregates of bile salts in which water-soluble (ionic) regions of the molecule face outward into aqueous solution, while the water¬insoluble (nonpolar) steroid nuclei face inward. Cholesterol is soluble in the interior of these spheroid micelles, and their cholesterol-carrying ability is further enhanced by the addition of lecithin, a polar phospholipid. Recently large cholesterol-phospholipid vesicles without associated bile salts have been shown in bile. The amount of cholesterol carried in bile vesicles and in micelles varies with the bile salt secretion rate.
Why do some persons develop gallstones while others do not? Supersaturation of choles¬terol in native bile solution is a necessary condition, but not a sole cause, of cholesterol gallstone formation, since supersaturation is frequent in the bile of fasting persons without gallstones. The other critical factor in determining whether gallstones form is the regula¬tion of the initiating process, cholesterol monohydrate crystal formation. In gallbladder bile that is lithogenic, there is supersaturation of cholesterol and also relatively rapid nucle¬ation of cholesterol crystals. There exists a dynamic interplay between forces for and against cholesterol nucleation and crystal growth in the gallbladder. These include the ac¬tions of specific proteins or apoproteins, gallbladder mucin, and gallbladder stasis.
Virtually all gallstones form within the gallbladder, but stones may form behind biliary
duct strictures, due to stasis, or in bile ducts after cholecystectomy.
There are not dangerous per se, but they can lead to complications like infection and obstructions.
Let me know as a new question if you have more questions. Good luck.