Ultrastructural changes in pancreatic acinar cells of rats after administration of 4-hydroxyaminoquinoline-1-oxide.

Ultrastructural changes in the exocrine pancreas 24, 48, 72 and 168 hours after a single intravenous injection of 4-hydroxyaminoquinoline-1-oxide (4-HAQO), at a dose of 14 mg.per kg., were observed in male rats. At 24 hours after administration, multiple focal degenerative lesion-like large vacuoles in the acini, and a decrease in zymogen granules with dilation of the rough endoplasmic reticulum cisternae in the acinar cells were marked. At 48 hours, acinar cell degeneration and necrosis progressively increased. The nucleus, especially, appeared to be disorganized and lysosome-like bodies with various sizes were frequently observed. At 72 hours, acinar cell degeneration persisted in the acini, and the interstitial space with infiltration of inflammatory cells appeared edematous. In addition, ductular-like cells, which resembled intercalated duct cells, possessing a light cytoplasm with occasional mitoses were observed around the duct lumen. At 168 hours, the exocrine pancreas was occupied with proliferated ductular-like cells. Furthermore, acinar cells and acini regenerated to the normal pattern were sometimes found. Thus, the exocrine pancreas degenerated progressively up to 48 hours after administration of 4-HAQO, gradually came to be repaired by degrees from 72 hours and then partly appeared to be regenerated at 168 hours. It is suggested that the ductular-like cell might be the precursor of the acinar cell in the regenerating process after injection of 4-HAQO.