The key difference between serous acini and mucous acini is that serous acini are secretory units that contain only serous cells, which are generally spherical in shape, while mucous acini are secretory units that contain only mucous cells, which are generally tubular in shape.
Normally, secretory cells are organized or arranged into secretory units called acini. Therefore, acini refers to any of the terminal saclike portions of a compound gland that contain secretory cells. Acini are classified according to the cell types they usually contain, such as serous acini (have only serous cells and are generally spherical in shape), mucous acini (have only mucous cells and are generally tubular in shape), and mixed acini (have a mixture of serous and mucous cells).
CONTENTS
1. Overview and Key Difference
2. What are Serous Acini
3. What are Mucous Acini
4. Similarities – Serous Acini and Mucous Acini
5. Serous Acini vs. Mucous Acini in Tabular Form
6. Summary – Serous Acini vs. Mucous Acini
What are Serous Acini?
Serous glands contain secretory units called serous acini. Serous acini are a grouping of serous cells that are generally spherical in shape. Serous acini secrete serous fluid, which is isotonic with blood plasma. This serous fluid contains enzymes, including alpha-amylase. Alpha-amylase is an enzyme that hydrolyses α bonds of large, α-linked polysaccharides (starch and glycogen). After hydrolyses by alpha-amylase, these polysaccharides yield shorter chains of disaccharide compounds called dextrins and maltose. Moreover, α–amylase is an endo glycohydrolase encoded by the gene known as Amy1.
Serous glands are more commonly found in salivary glands, such as in the parotid gland and submandibular gland. Serous glands can also be found in lacrimal glands in the eyes of marine mammals. Serous glands are found far lesser extent in the sublingual gland. Therefore, serous acini can also be present in glands like the parotid gland, submandibular gland, lacrimal glands, and sublingual gland.
What are Mucous Acini?
Mucous acini are secretory units that contain only mucous cells and are generally tubular in shape. Like goblet cells, mucous acini usually secrete mucus. Mucus is a watery carbohydrate-rich substance that is low in protein. The mucus provides a protective coating around the hard and soft tissues of the mouth. Mucous acini are found in submandibular and sublingual glands.
Mucus-producing cells in mucous acini stain very poorly with most of the stains. This is because these cells contain little rER (rough endoplasmic reticulum), and the mucin secretory granules of these cells react poorly with most stains. However, these mucus-producing cells in the mucous acini can stain by using PAS-Alcian blue (which stains mucus-producing cells in purple color).
What are the Similarities Between Serous Acini and Mucous Acini?
- Serous acini and mucous acini are two different types of secretory units in glands.
- They can be found in salivary glands such as submandibular and sublingual glands.
- Both acini produce saliva.
- They contain cells that perform important functions.
- Sometimes, in some glands, both serous acini and mucous acini can be found together, resulting in mixed acini.
What is the Difference Between Serous Acini and Mucous Acini?
Serous acini are secretory units that contain only serous cells, which are generally spherical in shape, while mucous acini are secretory units that contain only mucous cells, which are generally tubular in shape. Thus, this is the key difference between serous acini and mucous acini. Furthermore, serous acini secrete a protein-rich product containing various digestive enzymes. On the other hand, mucous acini secrete mucus, which is a watery, carbohydrate-rich substance.
The infographic below presents the differences between serous acini and mucous acini in tabular form for side-by-side comparison.
Summary – Serous Acini vs Mucous Acini
Salivary glands have three main cell types: acinar cells, ductal cells, and myoepithelial cells. Among them, glandular secretory end pieces called acini are very important as they produce saliva. Acini are secretory cells that are organized into secretory units. Serous acini and mucous acini are two different types of acini that can be found in salivary glands. Serous acini contain only serous cells, which are generally spherical in shape, while mucous acini contain only mucous cells, which are generally tubular in shape. So, this summarizes the difference between serous acini and mucous acini.
Reference:
1.“Serous Gland.” An Overview | ScienceDirect Topics.
2. “Human Structure Virtual Microscopy.” Indiana University School of Medicine Virtual Microscopy.
Image Courtesy:
1. “Trachea histology” By Lahari krishna – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Esophageal submucosal glands – biopsy, high mag” By CoRus13 – Own work (CC BY-SA 4.0) via Commons Wikimedia
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