Pancreatic acini - The secretory elements of the exocrine pancreas are long and tubular (but they are usually described as acini as they appear rounded or oval in sections). Their lumen is small. Secretory Cells - The cells lining the alveoli appear triangular in section, and have spherical nuclei located basally. In sections stained with haematoxylin and eosin the cytoplasm is highly basophilic (blue) paicularly in the basal pa. With suitable fixation and staining numerous secretory (or zymogen) granules can be demonstrated in the cytoplasm, specially in the apical pa of the cell. These granules are eosinophilic. They decrease considerably after the cell has poured out its secretion. With the EM the cells lining the alveoli show features that are typical of secretory cells. Their basal cytoplasm is packed with rough endoplasmic reticulum (this being responsible for the basophilia of this region). A well developed Golgi complex is present in the supranuclear pa of the cell. Numerous secretory granules (membrane bound, and filled with enzymes) occupy the greater pa of the cytoplasm (except the most basal pa). REF: Inderbir Singh's Textbook of Human Histology, seventh edition, pg.no., 298,299, 300.