Serous vs Mucus
Serous and mucus are two types of fluids produced by exocrine glands. They are released directly to outside from the glands through the ducts. These fluids have different physiology including their origin, composition, water percentage etc. However, both serous and mucus are important in providing protection for cell layers and organs.
Mucus is a viscoelastic, nonhomogenous fluid that contains watery matrix, glycoproteins, proteins, and lipids. Mucus is produced by mucous cells, which resemble to make mucous membrane and mucous glands. Mucous membranes can be found lining the respiratory system, digestive system, reproductive system, and urinary system. The term ‘mucosa’ is used to identify specific mucous membranes. For example, respiratory mucosa lines the respiratory tract, gastric mucosa lines the stomach, and intestinal mucosa lines the small and large intestines. Mucus serves as a lubricant and protects cell layers in the body. Also, it helps to remove bacteria and other foreign particles from the body.
Serous is a fluid that contains mainly water and some proteins such as amylase enzyme. It is produced by the serous cells, which are arranged as clusters called ‘acini’ in serous glands. Serous glands are largely found in the parotid gland and lacrimal gland. Serous may be also produced by mixed glands such as submaxillary gland. Mixed glands produce both mucus and serous. In addition, serous can be found in the space between lungs and pleural sac as ‘pleural fluid’, in the space between the heart and the pericardial sac as ‘pericardial fluid’, and in between the intestine and the peritoneal sac as ‘peritoneal fluid’. The main functions of serous are to help digestion of starch, allow organs to move freely, and prevent friction.
What is the difference between Serous and Mucus?
• Mucous cells in the mucous glands secrete mucus, while serous cells in the serous glands secrete serous.
• Clusters of serous cells are called serous acini, whereas the clusters of mucous cells are called mucous acini.
• Mucous acini are composed of larger cells, whereas serous acini are composed of smaller cells.
• Serous acini have narrow lumen while mucous acini have wider lumen.
• Nucleus of serous cell is spherical and is placed in the basal third of the cell, whereas that of mucous cell is flattened and is placed near the base.
• In H and E- stain, mucous cells appear pale blue, unlike the serous cells.
• The Golgi cell complex is clearly scene in mucous cells, unlike in serous cells.
• Mucus is thick and viscous fluid, whereas serous is more watery and less thick.
• Serous contains amylase enzyme, whereas mucus contains little or no enzymes.
• Serous helps to digest starch, whereas mucus mainly serves as lubricant and protection layer.
• Serous is discharged by exocytosis from serous cells, whereas mucus is released by rupturing the mucous membrane.
• Interdigitations between adjacent mucous cells are few, whereas Interdigitations between adjacent serous cells are more.
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