Mucoserous acini (singular acinus) or mixed

acini An acinus (; : acini; adjective, acinar or acinous) 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 secret ...

are mainly present in

submandibular The submandibular ganglion (or submaxillary ganglion in older texts) is part of the human autonomic nervous system. It is one of four parasympathetic ganglia of the head and neck. (The others are the otic ganglion, pterygopalatine ganglion, and ci ...

and

sublingual Sublingual (List of abbreviations used in medical prescriptions, abbreviated SL), from the Latin for "under the tongue", refers to the pharmacological route of administration by which substances diffuse into the blood through Tissue (biology), t ...

glands. Mucoserous acini differ from mucous acini in that the latter contain only mucous cells and are generally tubular in shape, whereas mucoserous acini contain a mixture of both serous and mucous cells. In mucoserous acini, mucous cells typically form the main structure of the acinus, with serous cells either interspersed among them or arranged as serous demilunes, crescent-shaped caps superficial to the mucous cells. Both cell types release their secretions directly into a shared lumen, contributing to a mixed, viscous and enzyme-rich fluid.

Structure

In mucoserous acini, mucous cells typically form the main body of the acinus, producing mucin, a glycoprotein that lubricates the oral cavity. Serous cells are often arranged as crescent-shaped caps known as serous demilunes, which overlay the mucous cells. These serous cells secrete a watery, enzyme-rich fluid containing proteins such as lysozyme, contributing to the antimicrobial properties of saliva. Both cell types release their secretions directly into a shared lumen, facilitating the combined mucous and serous output characteristic of these glands.

Histological Considerations

The appearance of serous demilunes in histological preparations is considered an artifact resulting from traditional fixation methods. During fixation, mucous cells may swell, displacing the serous cells into a crescent shape. Advanced fixation techniques have demonstrated that serous and mucous cells are more uniformly distributed within the acinus than previously thought.

Functional Significance

The mixed secretion from mucoserous acini plays a crucial role in oral health. The mucous component aids in lubricating the oral cavity, facilitating speech and swallowing, while the serous component contains enzymes that initiate the digestion of carbohydrates and possess antimicrobial properties, thereby contributing to the maintenance of oral hygiene.

References

Histology {{anatomy-stub