They represent an extension of the intercalated duct into each pancreatic acinus. Acini is the plural of acino whose root is the Latin word "acinus". The cells in each acinus are filled with granules containing the digestive enzymes. Examination showed that the serous cells and mucosal cells were aligned in the acinus. Secretory cells are found in a group, or acinus (plural, acini). But after a few minutes of compression, they form an acinus, Euclidian, on the right. Each acinus is incompletely separated by an interlobular septa. The term "acinus" is considered synonymous with alveolus by some sources, but not all.