THE LOCALIZATION OF GASTRIN‐LIKE IMMUNOREACTIVITY (GIR) IN THE ALIMENTARY TRACT OF THE SHEEP

Using an antiserum raised against synthetic cholecystokinin (CCK 8), the localization and distribution of gastrin‐like or CCK‐like immunoreactivity was investigated in the alimentary tract of the sheep by the method of indirect immunofluorscence. Immunoreactive cells were confined to the mucosa of the abomasal antrum and the proximal small intestine and were not observed in the oesophagus, rumen, reticulum, omasum, abomasal fundus, ileum, large intestine, pancreas or gall‐bladder. Antral tissue was fixed for electron microscopy and stained by the unlabelled antibody peroxidase anti‐peroxidase procedure. Stained cells were found across the entire thickness of the mucosa. Adjacent sections stained with heavy metals revealed secretory granules with an electron‐dense core and some G cells possessed a tuft of microvilli projecting into the glandular lumen.