Effects of partial surgical pancreatectomy in rats. I. Pancreatic regeneration.

The capacity for pancreatic regeneration in male Wistar rats of average weight 176 g was determined after surgical resection of 50, 70, or 90% of the pancreas. In control animals of this weight pancreatic growth was still taking place but ceased after 2 months. Growth of the residual pancreas in resected animals over this period was greater than in controls and the final weight of the residual pancreas was 21, 32, and 78% greater than that of the corresponding segments in sham-operated animals after 50, 70, and 90% resection respectively. Proliferation of acinar cells was assayed by autoradiographic detection of tritiated thymidine incorporation in controls and after 90% resection. Proliferation of acinar cells in control animals during the first 2 weeks of the experiment was significantly higher than at later times when it fell to very low levels. Proliferation in 90% resected animals was markedly higher than in controls from 2 to 5 days after resection and, together with the limited hypertrophy occurring at this time, adequately accounted for the increase in weight of the residual pancreas during the first 2 weeks. We were unable to explain the increase in pancreatic weight in control or resected animals between 2 weeks and 2 months either in terms of hypertrophy or hyperplasia of acinar cells.