Radiological and histological analyzes of the structural changes in the rat parotid gland following release of Stensen's duct obstruction

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Sialography is the preferred method for diagnosis and treatment planning in obstructive sialoadenitis. Many experimental studies reported the changes following duct obstruction. However, sialographic changes following release of obstruction have not been studied. The present study was undertaken to clarify ; (1)the relationship between sialographic and histological changes, (2)the effects of duration and pressure of obstruction on gland recovery, (3)the possibility to establish sialographic features indicating the prognosis for gland recovery. Stensen's ducts of rat parotid glands were obstructed over 2 time courses under 3 varying pressures in order to induce variant degrees of degenerative changes on glandular tissue. The structural alteration resulting from release of obstruction was investigated by means of qualitative and quantitative microsialography and histology. Gland structure was assessed visually from the latter and classified into 6 groups ; normal, recovery and slight, moderate and severe degeneration and fibrous groups. Microsialograms were evaluated based on these histological groups. Qualitatively, microsialograms of the operated glands showed stricture at the obstructed region and dilation of the major ducts. Hsitological defferences between recovery and degeneration glands were reflected on the figures of peripheral ducts. The former showed a branch-like morphology similar to that of the normal group, and the latter showed small granule-like figures. Quantitatively, dilation of major ducts in the recovery group decreased compared with the other operated groups. With regard to degeneration and fibrous groups, there were no distinct sialographic features which correlated with the degree of degeneration observed histologically. Duration and pressure of obstruction were highly predictive of prognosis for recovery of the glands. At the time of release of obstruction, however, it seems difficult to determine the prognosis for gland recovery by sialogra