The fine structure of pancreatic stones as shown by scanning electron microscopy and x-ray probe microanalyser
SummaryTo delineate the process of pancreatic stone formation, stones from four patients were studied with a scanning electron microscope and X-ray probe microanalyser.The stones consisted of a central core and surrounding shell. Two kinds of stones were demonstrated:one had a core composed of a calcium-rich amorphous substance and interlacing fibrils; the other had a core consisting of multiple cavities with smooth walls composed of a calcium-deficient amorphous substance.The shells showed a common structure: zones of layers or bands of a calcium-rich amorphous substance, network fibrils filled with a calcium-rich amorphous substance, and laminated parallelogrammic or polygonal plates of calcite parallel to the surface in one layer and oblique or perpendicular in the next layer. Calcium was in the crypto-crystalline state as well as crystalline state of calcite. Crystalline calcite showed spiral and epitaxial growth along with findings of dissolution, resembling cholesterol crystals of gall stones. Pancreatic stones are probably formed through central core formation and layered growth of a shell. Comparison of stones and protein plugs suggests that protein plugs can grow to stones with calcite deposition accompanied by precipitation of network fibrils and an amorphous substance.
Differences of pancreatic stone morphology and content in patients with pancreatic lithiasis
Pancreatic stones from 25 patients were compared by morphological and/or radiological examination. Twenty patients, mostly alcoholics, had calcified stones. Five (four nonalcoholic women) had radiolucent stones. Aspect and consistency of calcified stones varied from compact and resistant to coralliform and brittle but were identical in the same patient. In the coralliform type, organic fibrils with a diameter up to 10 μm and a length up to a few centimeters were observed, strongly attached to mineral crystals. The lithostathine (formerly called pancreatic stone protein, PSP) content was estimated in each stone significantly lower in the populations with larger stone mass, compared to populations with small amounts of stones. Transparent stones were built up of an amorphous material solubilized at acidic pH and corresponding to degraded forms of lithostathine-S (S for secretory). In one patient, we followed over seven years the evolution of a radiolucent calculus. We observed that the radiolucent core occurred first, and was secondarily wrapped in a calcified shell. We conclude that morphological differences observed in this study among pancreatic stones suggest that different mechanisms have been involved in their formation. Among them, lithostathine transformation into insoluble polypeptides may provide different types of protein aggregates, some of them being able to promote CaCO3 apposition and others having no affinity for calcium.
Effects of chronic ethanol administration on canine exocrine pancreatic secretion.
The effects on pancreatic exocrine secretion of an acute intravenous ethanol injection (1.3 g/kg) and of 12 months of intragastric alcohol feeding (2.0 g/kg) were studied in 5 dogs provided with chronic pancreatic and gastric fistulae (Thomas cannula). Dogs were subjected either to a continuous intravenous injection of secretin alone (GIH, 1.0 CU/ kg/h) or associated with CCK (GIH, 3.0 U/kg/h). Twelve months of alcohol treatment first abolishes and then reverses the inhibitory effects of acute intravenous ethanol on pancreatic secretion. Ethanol treatment, in its earlier stages, provokes cholecystokinin-mediated higher plateau secretory values. This reflects increased sensitivity of ‘pancreon’ cells to the hormone. A subsequent fall of plateau values indicates a lesion of the gland. This is apparently related to the excretion of protein plugs and microstones through the main pancreatic duct.