The relationship between synthesis of secretory products and reducing capacity in pancreas and parotid acinar cells.

The secretory products in exocrine pancreas acinar cells in utero were found to reduce osmium tetroxide. This reducing capacity was also exhibited by adult pancreas and parotid glands in different phases of synchronized secretion, and after single or chronic administration of a secretagogue, pilocarpine or isoprenaline. In utero, the reducing capacity appeared in the pancreas concomitantly with the synthesis of secretory products, and was limited to the transitional vesicles on the cis Golgi side. After birth, osmium staining occurred in the cis Golgi vesicles and cisternae of both glands. In the chronically-treated parotid gland, where the occupational programme for secretory proteins had been altered, the reducing capacity was diminished, resembling that in embryonic exocrine pancreas.