Immunocytochemical and ultrastructural characterization of endocrine cells and nerves in the intestine of Rana temporaria

Endocrine cells have been identified in the intestine of the frog Rana temporaria after application of the Grimelius and Masson-Fontana techniques. These endocrine cells were examined using immunocytochemical techniques on paraffin and semithin sections for light microscopy. After testing 19 antisera. 12 immunoreactivities were identified. Numerous serotonin-, somatostatin- and GLP-1-immunoreactive cells; a moderate number of PYY-, glucagon-VIP-, gastrin/CCK-immunoreactive cells and few human PP-, bombesin-, substance P- and neurotensin-immunoreactive cells were found. VIP- and met-enkephalin were identified in nerve fibers of the muscular layer. Using semithin-thin sections five types of endocrine cells (serotonin-, somatostatin-, gastrin/ CCK-, glucagon- and bombesin-immunoreactive cells) have been characterized according to their immunocytochemical reaction and the ultrastructure of the secretory granules.