In the Rana catesbeiana exocrine pancreas 2 types of serozimogenic cells could be observed. They were called light and dark cells. The light cells were observed in a greater number and presented the GER cisterns predominantly located in the basal region of the cell and the vesicular forms of the GER mainly in the supranuclear region. The Golgi complex was well developed and the secretory granules were grouped in the cell apex. The mitochondrion were distributed by the cytoplasm and the nucleous appeared in the basal region of the cell and presented a pale and vesiculous profile that made the nucleolus evident. The dark cells were observed in smaller quantity and in this cell occurred a predominance of GER vesicles. The cytoplasmic matrix presented an electron-dense appearance and a large quantity of free ribosomes. The Golgi complex is poorly developed, the secretory granules and the mitochondria are scarce. We could observe besides the light and dark cells, the centroacinar and the intermediate cells. The centroacinar cells lay in the luminal border of the acinar cells. They presented an electron-lucent cytoplasmic matrix where could be noted a few GER profiles and the secretory granules were absent. The intermediate cells showed, intermingled within the same cell, the zimogenic and the endocrine-like alfa and beta Langerhans granules.