• 85% of the pancreas is composed of acinar cells which are the excretory portion of the gland
• The acinus has a single layer of polygonal cells surrounding a small central lumen. There are numerous different pathways by which the secretions of the acinus may reach the ductal system.

• Acinar cells contain

1. A large central nucleus
2. Lots of ER arranged in parallel stakes
3. apical granular eosinophilic cytoplasm with
4. lots of zygmogen granules
5. lots of secretory granules

• The secretory granules of the acinar cells fuse with the apical plasma membrane and expel their contents into the lumen.
• Adjacent acinar cells are joined by apical junction complexes zonula occludens and adherans and desmosomes (macula adherans) join the acinar cells around their lateral surfaces.
• Each acinus is surrounded by a continuous basement membrane (Mills ET AL 2007).