Sixteen rats underwent a total gastrectomy with an end-to-end anastomosis between the esophagus and duodenum. After either two or four weeks, the entire pancreas was excised and isolated lobules were incubated for 60 min in Krebs-Ringer-Hepes solution either with or without addition of ceruletide (5 X 10(-10) g/ml). Amylase was determined every 15 min in the supernatant medium. Measurements of amylase, lipase, trypsin, DNA and total protein were carried out in the homogenized pancreatic tissue. Morphometry was performed via light microscopic analysis. Two weeks following gastrectomy there was an increase in pancreatic wet weight, DNA, total protein and enzyme content (except lipase). Four weeks after surgery, pancreatic weight, amylase and trypsin increased further, whereas DNA content and lipase content remained stable. The DNA concentration decreased, and the size of exocrine pancreatic cells increased. In vitro, amylase discharge increased only after four weeks. The experiments demonstrate a short-term adaptation of the rat exocrine pancreas following total gastrectomy in the form of cellular hyperplasia (after 2 weeks), and hypertrophy (after 4 weeks), and enzyme dissociation.