The formation of zymogen granules in the pancreas

Electron-dense, granular (rarely vesicular) bodies, some 30 m/x or more in diameter, are seen lying in the ground cytoplasm in the vicinity of the smooth-surfaced membranous complex. They often appear to be embedded in amass of amorphous material, which is of about the same electron-density as the granules themselves. Granules and vesicles, similar in appearance to those mentioned above, have also been seen in contact with large vacuoles that appear to be developing into zymogen granules. The membrane that delimits such vacuoles sometimes appears to be disrupted, particularly where the granules seem to establish contact with the vacuoles. These vacuoles give the impression of having accumulated granular or vesicular material within them. They may perhaps be connected with the process of formation of zymogen granules.