Microstructure of gallstones.

Electron microprobe analysis, x-ray diffraction, and infrared spectroscopy have been used to investigate the nature and arrangement of materials present in gallstones. Calcium phosphate and carbonate deposits present centrally in many stones were mixed with a pigmented phase containing copper and protein. In several stones, the central calcium deposits were surrounded by discrete adjacent layers of calcium bilirubinate and cholesterol. The calcium bilirubinate layer was distinguished from other pigmented layers by its higher protein content and increased iron/copper ratio. This sequence of calcium salt and cholesterol deposition occurred in the outer layers of some stones. The phase relationships shown by the present study are consistent with a biphasic mechanism of stone growth in which calcium salts and lipid were alternately deposited. Calcium salt precipitation has been inferred to initiate the sequence as calcium salts were found at the stone centers. The layer sequence has been discussed in terms of some possible effects of damage to the gallbladder wall caused by the calcium salt deposits.

Electron probe microanalysis in the study of gallstones.

Detailed information on the structure and composition of gallstones was obtained using an electron probe microanalyser in conjunction with the other methods. Gallstones were studied layer by layer without greatly disturbing the arrangement of the materials present. Elements, including trace elements such as copper, iron, and manganese, were identified and their distributions mapped. The range of the method was extended to determine the character and distribution of certain chemical groups present by treating sections of gallstone with reagents which contained easily detected elements. The nature of the bonding of the sulphur in the stones was studied by examining the sulphur-X-ray spectrum. Pigmented sulphur-containing deposits were found to contain sulphur in a low valence state but taurine conjugates and the sulphate groups of mucosubstances were not detected. Microcrystalline apatite present in the stones contained some manganese and seemed to be implicated in the absorption of the low valence sulphur compound and in the nucleation of some stones.