Experimental sialography: the effects of retrograde infusion of radiographic contrast media on salivary gland morphology and function. A review article.

An experimental model for sialography, involving retrograde infusion of contrast medium into the rat submandibular gland under continuous pressure monitoring, was developed. Morphologic alterations induced during infusion of water- and lipid-soluble radiographic contrast media and the distribution of the media were examined with light and electron microscopy. An uneven distribution of the media throughout the tissue and variations in the degree of the alterations in different parts of the gland were seen at all stages of filling. The changes primarily consisted of dilation of the luminal system, which successively became more pronounced as infusion continued. Infusion of the lipid-based medium consistently resulted in more severe alterations, including changes in the acini. Tracer studies showed that the water-soluble medium leaked out through the intercellular spaces and to the surrounding tissue, whereas the lipid-based medium appeared to be confined to the luminal space. Ductal filling with either medium resulted in a relatively fast recovery; after prolonged infusion, recovery was slower and additional alterations occurred. The acini showed confluence of secretory granules and vacuole formation. After infusion of the lipid-based compound, autophagic vacuoles and granulomatous alterations developed. Prolonged infusion with either medium resulted in atrophy of the parenchyma and connective tissue proliferation in some glands. An inflammatory infiltrate was present in all glands during the recovery period. Functional alterations, primarily consisting of a decrease in flow rate, were noted after prolonged infusion. The increase in intraluminal pressure induced during infusion was most likely the primary cause of the alterations. In addition, the presence of contrast medium contributed to the long-term effects of the procedure.