Atlas of plant and animal histology

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Animal tissues.
Glandular epithelium.


Mucous acini
Serous acini
Excretory ducts
Myoepithelial cells
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Epithelium: salivary gland
Organ: submaxillary salivary gland, exocrine gland.
Species: mouse (Mus musculus; mammal).
Technique: 8 µm thick sections stained with haematoxylin-eosin.
icono Salivary gland This image is from rat submaxilar salivary gland.
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Exocrine glands can be classified according to the type of products they release. Salivary glands are exocrine glands that produce and release saliva. They may contain two types of secretory cells: mucous and serous, that form mucous and serous acini, respectively. Mixed acini with both serous and mucous cells can also be found (see figure 1). Mucous secretory cells show clear cytoplasm because they mostly contain mucopolysaccharides, which do not retain common dyes, and a basal flattened nucleus. Serous secretory cells show a darker cytoplasm due to the high enzymatic content, with amylases as the most abundant enzymes. The nucleus is located in a central position and is rounded. Myoepithelial cells, showing a narrow cytoplasm and a very flattened nucleus, can be found wrapping excretory ducts and some acini. These cells can make contractile movements, which help to expel the gland content.

Types of acini
Figure 1. Types of acini: mucous, serous and mixed. Mixed glands have separated mucous and serous acini, but some glands may have serous and mucous cells intermingled in the same acinus. The serous demilunes on the right (bottom part) are observed at light microscopy, but they are actually artifacts. (modified from Krstić, 1989).

In humans, there are several types of salivary glands: parotid, sublingual, submaxilar and accessory salivary glands, which are smaller and scattered. Only sublingual and submaxilary can release both mucous and serous substances. They are mixed glands. Small salivary glands are mucous. All salivary gland release their content into the oral cavity after the stimulation by the autonomous system.

Más imágenes

Submaxilar salivary gland
Submaxilar salivary gland. Mucous acini and an excretory duct can be observed.
Sublingual salivary gland
Sublingual salivary gland. Black arrows point to the secretory acini and red arrow to the excretory duct.
Sublingual salivary gland.
Sublingual salivary gland of a rat. Serous and mucous acini can be observed.
Submaxilar salivary gland
Submaxillary salivary gland of a rat. The serous part is located on the left and the mucous part on the right.
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