ENDOCRINE TISSUE ASSOCIATED WITH THE PANCREATIC DUCTAL SYSTEM - A LIGHT AND ELECTRON-MICROSCOPIC STUDY OF THE ADULT-RAT PANCREAS WITH SPECIAL REFERENCE TO A NEW ENDOCRINE ARRANGEMENT

Background: A substantial part of the endocrine pancreas has been prev iously described as being located either close to the excretory ducts as small clusters of endocrine cells and as Islets of Langerhans, or a ssociated with the ducts as single endocrine cells scattered through t he ductal epithelium. Methods: Four Wistar white adult rats were sacri ficed and perfused via the thoracic aorta with 2.5% glutaraldehyde. Af ter the usual treatment for the transmission electron microscopy, piec es of pancreas were sectioned consecutively for light microscopy. Cons ecutive ultrathin sections were performed in the most interesting case s. Results: The observations previously reported were confirmed. In ad dition, a new endocrine arrangement was detected and described as buds of endocrine cells (mainly B-cells) protruding from the ductal epithe lium into the surrounding tissue. Conclusions: The authors propose to explain the endocrine buds as components of the gastro-entero-pancreat ic system or as a stage of an endocrine pancreatic ''neo-histogenesis' ' occurring in the adult rat pancreas. (C) 1994 Wiley-Liss, Inc.