Ann Anat 189 (2007) 157—167 A co-localization study on the ovine pancreas innervation Marcin Bartlomiej Arciszewski à , Anna Zacharko-Siembida Department of Animal Anatomy and Histology, Faculty of Veterinary Medicine, Agricultural University, Akademicka 12, 20-033 Lublin, Poland Received 3 April 2006; accepted 5 September 2006 KEYWORDS Immunohisto- chemistry; Neuropeptides; Autonomic nervous system; Pancreas; Sheep Summary The expression of DbH and several neuropeptides was investigated in neuronal elements of the ovine pancreas using double immunocytochemical stainings. Immunoreactivities to DbH, NPY, VIP and SP were seen to various extents in nerve terminals associated with the acini, islets, ducts, blood vessels, interlobular connective tissue as well as in the neurons of intrapancreatic ganglia. The expression of CGRP was limited to nerve fibers lying in the connective tissue septa, amongst the acini and in close vicinity to the pancreatic blood vessels. Single GRP- positive nerve endings were located around the acini, ducts and in the interlobular connective tissue. With the exception of the ductal system in a co-localization of NPY with DbH was frequently found in all regions of the pancreas. Moderately numerous blood vessel- associated VIP-positive nerve fibers as well as the vast majority of VIP-containing intrapancreatic neurons were found to co-express DbH. Single SP-immunoreactive (IR) nerve fibers of the exocrine pancreas and interlobular connective tissue as well as SP-positive intrapancreatic neurons additionally showed the presence of DbH. The co-localization of VIP and NPY was found in nerve terminals located around the blood vessels and acini, in the connective tissue septa as well as in numerous pancreatic neuronal perikarya. Rare nerve terminals located between the acini and around small blood vessels as well as several neurons of intrapancreatic ganglia were VIP-IR/ SP-IR. Simultaneous expression of SP and CGRP was found in nerve fibers supplying large pancreatic arteries and veins, interlobular connective tissue and, occasionally, around the acini. Throughout the pancreas the population of CGRP-positive nerve endings showed lack of VIP and NPY. In a moderate number of GRP-containing nerve fibers, a co-expression of NPY was noted. Nerve terminals containing both GRP and VIP were detected sporadically, whereas none of the GRP-positive nerve terminals showed expression of SP. ARTICLE IN PRESS www.elsevier.de/aanat 0940-9602/$ - see front matter & 2006 Elsevier GmbH. All rights reserved. doi:10.1016/j.aanat.2006.09.002 à Corresponding author. Tel.: +48 81 445 65 96; fax: +48 81 445 65 96. E-mail address: marcisz@tenbit.pl (M.B. Arciszewski).