What is acini?

Acini (singular: acinus) are small, round, and berry-shaped structures in the body that are found in various organs like the pancreas, lungs, salivary glands, prostate, and mammary glands. They are responsible for secreting substances like enzymes, hormones, mucus, and milk into ducts that transport these substances to other parts of the body.

Acini are composed of a cluster of cells, which are polarized with one end facing the lumen (central cavity) and the other end attached to the basement membrane. The luminal surface of acinar cells contains many small invaginations called microvilli, which increase the surface area for secretion. In addition, they also have numerous secretory granules that contain the substances to be secreted.

The structure of acini varies in different organs. For example, in the pancreas, acini are organized into lobules, which are separated by connective tissue septa. Each acinus has a central lumen, surrounded by acinar cells that secret digestive enzymes into the pancreatic duct. In the mammary gland, acini are organized into lobules that are connected to the mammary duct system. The glandular tissue within the acini secretes milk during lactation.

The proper functioning of acini is essential for the normal physiological processes in the body. Dysfunction of acini can result in various pathological conditions such as pancreatic insufficiency, cystic fibrosis, chronic obstructive pulmonary disease (COPD), and breast cancer.