Acinus

Acinus
Illustrated section of pancreas of dog. X 250. (Alveolus labeled at center top.)
Centroacinar cells
Code	TH H2.00.02.0.03050

An acinus (adjective: acinar, plural acini) refers to any cluster of cells that resembles a many-lobed "berry," such as a raspberry (acinus is Latin for berry). The berry-shaped termination of an exocrine gland, where the secretion is produced, is acinar in form, as is the alveolar sac containing multiple alveoli in the lungs.

Exocrine glands

Acinar exocrine glands are found in many organs, including:

• the stomach
• the sebaceous gland of the scalp
• the salivary glands of the tongue
• the liver
• the lacrimal glands
• the mammary glands
• the pancreas
• the bulbourethral (Cowper's) glands

The thyroid follicles can also be considered of acinar formation but in this case the follicles, being part of an endocrine gland, act as a hormonal deposit rather than to facilitate secretion.
Mucous acini usually stain pale, while serous acini usually stain dark.
The term "acinus" is considered synonymous with alveolus by some sources, but not all.

human acinar cells

The Lungs

The respiratory bronchioles in the lungs terminate in acini, many-lobed sacs containing groupings of alveoli.

See also

• Intercalated duct

External links

• acinus at eMedicine Dictionary