Submaxillary gland recovery from obstruction. II. Electron microscopic alterations of acinar cells

Abstract

The recovery of secretory activity by acinar cells was studied in rat submaxillary glands after the removal of ligatures following 31 days of obstruction. Evidence of cell death or mitotic activity is extremely rare, indicating that the observed changes occur in the original cell population and that recovery is not dependent on de novo cell differentiation. The ultrastructural character of secretion granules changes from very dense, sometimes crystalloid, forms early in recovery, to lighter heterogeneous granules, to granules with distinct ropelike aggregations of secretory material, and finally to the characteristic mature granules containing a sparse uniform distribution of filaments. The filamentous secretory product of later time periods is demonstrated in Golgi saccules, in granules, and in luminal spaces. The filaments are about 80 A wide. RER and Golgi cisternae undergo complementary alterations: they are sparse in early periods when few granules are present and increase as granules increase and become more mature. In an early phase of recovery, the lumina of acini are filled with dense material which has membranelike characteristics.