The onset of secretion is marked by hypertrophy of the Golgi material. During the secretory phase the mitochondria lie parallel to the long axis of the cell. Secretory granules are first visible in close association with the Golgi material. Feeding brings about the evacuation of the secretion. Evacuation of secretion is total; regeneration of the cell precedes the next secretory phase.
The Golgi material enlarges during the onset of secretion. Few changes were observed in the morphology of the mitochondria. Secretory granules are first visible in close association with the Golgi material. Later they move towards the acinar lumen. Feeding brings about evacuation of the secretion granules, but total evacuation does not take place.
The morphology of the Golgi material changes considerably during the production of the secretory granules. Granular mitochondria predominate after a 24-hours' fast. Rods and filaments are prevalent after feeding. During the secretory phase the mitochondria lie parallel to the long axis of the cell. The secretory granules are first visible in association with the Golgi material. Free secretory granules are not visible until 6 hours after feeding.