epithelial / salivary glands, serous gland, mucous gland, mixed gland- discussion, viva

Epithelial / Salivary glands

1. How many salivary glands are present and where are they located?
• Serous or parotid salivary gland- largest glands located anterior and inferior to external ear
• Mucous or sublingual salivary gland- smallest glands located inferior to tongue
• Mixed or submandibular gland- small glands located inferior to mandible in the floor of mouth
2. What type of glands are salivary glands functionally?
• They are exocrine glands
3. What type of glands are salivary glands structurally?
• They are compound tubuloacinar glands
4. Where and how do they pour their secretion?
• Secretions are poured into the mouth through their large excretory ducts
5. What are the components of salivary glands?
• Cellular secretory units- acini
• Excretory ducts
6. What are acini?
• Acini are small, sac like dilations at the terminal end of intercalated ducts.
7. What are intercalated ducts?
• Intercalated ducts are the first segments of the excretory duct system attached to acini
8. What are different types of acini?
• Serous acini- made up of serous cells which are pyramidal in shape. Spherical or round nuclei are present at basal half and secretory granules in the apical region of the cells
• Mucous acini- made up of mucous cells which are columnar or pyramidal in shape. Flat nucleus present near the basement membrane and cytoplasm completely filled with mucus
• Serous demilune- Serous cells form a crescent or moon shaped cap over the mucous cells which is called serous demilune. They discharge their secretion into lumen through canaliculi present between the mucous cells
9. What are myoepithelial cells?
• Myoepithelial cells are flattened cells that surround both serous and mucous acini.
• They are highly branched and contractile in nature
• They are also called basket cells
• They are located between the basement membrane and the secretory cells
10. Details about excretory ducts
• Intercalated ducts- they are lined by low cuboidal epithelium. Initially all acini empty their secretions into intercalated ducts and part related to acini is surrounded by myoepithelial cells
• Striated ducts- intercalated join to form striated and are lined by columnar epithelium with basal infoldings of the cell membrane with numerous mitochondria which gives striated appearance
• Intralobular ducts- striated join to form intralobular ducts and are lined by columnar epithelium
• Interlobular ducts- intralobular join to form interlobular ducts and are lined by columnar epithelium
• Interlobar ducts- interlobular join to form interlobar ducts and are lined by stratified cuboidal or columnar epithelium
11. What is the arrangement of connective tissue in the glands?
• The whole gland is surrounded by connective tissue capsule.
• The gland is divided into lobes and lobules by the connective tissue fibers.
12. What are the differences between the mucous, serous and mixed salivary glands?

Types	Serous	Mucous	Mixed
Connective tissue	Well developed connective tissue capsule. Interlobular connective tissue with vessels and adipose tissue.	Well developed connective tissue capsule. Well developed connective tissue septa.	Well developed connective tissue capsule and stroma.
Acini (alveoli)	Serous.	Mucous.	Seromucous.
Cells	Pyramidal in shape with round nuclei at the base. Darkly stained apical cytoplasm because of the zymogen granules.	Globular in shape. Flat and condensed nuclei, at the basement membrane. Cells appear empty in H and E staining, because during the   processing mucinogen granules are washed off.	Both serous and mucous alveoli present. Demilunes or crescents of Gianuzzi, are the appearance of the sectioned serous alveoli seen as half moon or crescent shape over the mucous alveoli.
Duct system	Numerous inter lobular, intra lobular and  intercalated ducts. Lined by stratified to simple columnar to low cuboidal   epithelium.	Intercalated ducts are very rare or absent, more nonstriated intralobular ducts. Lined by stratified to simple columnar to low cuboidal   epithelium.	Few intercalated, more striated ducts. Lined by stratified to simple columnar to low cuboidal   epithelium. Serous demilunes discharge the secretion through the intercellular canaliculi located between the mucous cells.
Secretion	Watery secretion rich in enzymes and antibodies.	Viscid secretion.	Both watery as well as the viscid secretions.
E.g. Salivary gland	Parotid.	Sublingual.	Submandibular.