[The immunhistochemical investigation of trypsin and trypsin-like-activity in the small intestine, pancreas and isolated Langerhans islets. A light-, fluorescent- and electron microscopic study (author's transl)].

By means of the indirect immunofluorescence and immunenzyme technique trypsin and trypsin-like activity in fixed cryostate sections of pancreas and gut and pellets of isolated pancreatic islets respectively were investigated using specific antiserum against trypsin. The enzyme was demonstrated in the cytoplasma of the acinus cells, the epithel cell of the intercalated ducts and the excretory (interlobular) ducts of the exocrine pancreas. By light and fluorescence microscopy we could also localize a high activity in pancreatic islets. Results taken from electron microscope show the enzyme in the region of the peripheral endoplasmatic reticulum, the surface of the mitochondria, the zymogen granules of the acinus cells and in the region of the membranes of the endoplasmatic reticulum and in the granules of the B-cells of the pancreatic islets. These results are discussed in correlation with biochemical data concerning the importance of trypsin/trypsin-like activity in the specific conversion of prohormones into hormones.