IMMUNOCYTOCHEMICAL LOCALIZATION OF PROSTAGLANDIN ENDOPEROXIDE SYNTHASE IN THE BOVINE INTESTINE

The localization of prostaglandin (PG) endoperoxide synthase in bovine intestine was examined immunocytochemically with polyclonal antibody raised against PG endoperoxide synthase purified from bovine seminal g lands. The most intense positive staining reaction for the enzyme was present in mast cells. Mast cells were found to be widely distributed in the intestinal wall, and were particularly numerous in the lamina p ropria. Most of the mast cells in the lamina propria of the intestinal villi were elongated and oriented with their long axis parallel to th e plane of the absorptive epithelium. In whole mount preparations of j ejunal villi, mast cells were seen to form a two-dimensional network i n the lamina propria. In addition to mast cells, smooth muscle cells o f the inner circular muscle layer and muscularis mucosae, nerve cells and fibers, endothelial cells of arterioles, and serosal epithelial ce lls also showed faint to moderate staining for the enzyme. These resul ts suggested that mast cells are the major source of PGs in the bovine intestinal wall. The characteristic arrangement of mast cells in the intestinal villi may be related to their functions in this portion of the bovine intestine.