TRANSITIONAL CELLS IN THE REGENERATING PANCREAS

We examined the spectrum of intermediate cell types in the regeneratin g pancreas as duct epithelial cells progressed through their different iation pathway to become mature endocrine cells. The model used was tr ansgenic mice in which the pancreatic islets continue to grow during a dulthood, unlike normal mice whose islet cell formation ceases early i n life. Because the intermediate cells migrated into islet-like cluste rs at specific locations, we propose a specific pathway for islet deve lopment. Endocrine cells are derived from duct cells co-expressing a d uct cell antigen, carbonic anhydrase II (CA II) and an exocrine enzyme , amylase. The CA II/amylase cells become amylase/endocrine intermedia te cells as they exited from their lumenal location. The abluminal amy lase/endocrine cells continue to differentiate to multihormone-bearing young endocrine cells, which migrated to form clusters with other dif ferentiating endocrine cells.