2023 Volume 38 Issue 5 Pages 303-317
In this study, serial sections of rat pancreatic tissue were examined using light and transmission electron microscopy to determine the epithelial cellular arrangement. One or more large-sized acinar cells with secretory canaliculi were discovered wedged into a small-sized intercalated duct cell line and connected with sequential acinar cells. These cells were shown to have direct contact with the outer surface of the intercalated duct without a basement membrane, forming secretory canaliculi branching from an intercalated ductal lumen along with the intercalated duct cells. Most islets of Langerhans lacked portions of peripheral basement membranes, thus allowing acinar cells or intercalated duct cells to have direct contact with endocrine cells in the peripheral islets. This resulted in formation of secretory canaliculi or intercalated ducts along with those endocrine cells. Based on these findings, it is speculated that differentiated endocrine or acinar cells wedged into peripheral portions of immature pancreatic duct cell lines individually proliferate out of the pancreatic ducts, with adjacent clusters of endocrine cells merged into an islet, after which the proliferating acinar cells along with secretory canaliculi establish direct contact with the outer surfaces of pancreatic ducts and islets.
