Acinus

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Acinus (plural: acini) is a term used in anatomy to describe a cluster of cells that resemble a many-lobed "berry," such as a raspberry or blackberry. The term is derived from the Latin word for "berry." Acini are found in various glands throughout the body and are responsible for the secretion of various substances.

Structure

Acini are typically composed of a cluster of secretory cells that surround a small central lumen. These cells are often arranged in a spherical or tubular shape. The secretory cells of an acinus are usually epithelial cells that produce and release substances into the lumen, which then drains into larger ducts.

Types of Acini

Acini can be classified based on the type of secretion they produce:

• Serous acini: These acini secrete a watery, enzyme-rich fluid. They are commonly found in the parotid gland and the pancreas.
• Mucous acini: These acini secrete a viscous, mucous-rich fluid. They are typically found in the sublingual gland.
• Mixed acini: These acini contain both serous and mucous cells and produce a combination of watery and viscous secretions. They are found in the submandibular gland.

Locations

Acini are found in several different glands in the body, including:

• Salivary glands: The parotid gland, submandibular gland, and sublingual gland all contain acini that produce saliva.
• Pancreas: The exocrine portion of the pancreas contains acini that secrete digestive enzymes into the duodenum.
• Liver: The liver contains acini that are involved in the production and secretion of bile.
• Mammary glands: The mammary glands contain acini that produce milk during lactation.

Function

The primary function of acini is to produce and secrete various substances necessary for bodily functions. For example:

• In the salivary glands, acini produce saliva, which aids in digestion and keeps the mouth moist.
• In the pancreas, acini produce digestive enzymes that help break down food in the small intestine.
• In the liver, acini produce bile, which helps in the digestion and absorption of fats.
• In the mammary glands, acini produce milk to nourish infants.

Clinical Significance

Disorders of acini can lead to various medical conditions. For example:

• Pancreatitis: Inflammation of the pancreatic acini can lead to pancreatitis, a condition characterized by abdominal pain and digestive issues.
• Sjogren's syndrome: This autoimmune disorder affects the acini in the salivary and lacrimal glands, leading to dry mouth and dry eyes.
• Cystic fibrosis: This genetic disorder affects the acini in the pancreas, leading to thickened secretions and digestive problems.

See Also

• Gland
• Exocrine gland
• Endocrine gland
• Secretory cell
• Epithelium