There are three pairs of major salivary glands



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Salivary gland
There are three pairs of major salivary glands:

(Parotid, sublingual, submandibular) glands. In addition, there are minor numerous small glands located in the submucosa of the oral cavity (labial glands) cheeks (buccal glands) tongue (lingual glands – palatine gland)




  • These glands are compound tubuloalveolar glands.

  • They are consisting of lobes and further subdivided by C.T. trabeculae into lobules. Blood vessel, lymph vessels were present within C.T.

  • The secretory portion (elements) is composed of acini or alveolar, tubular or tubuloalveolar


General structure

- C.T stroma

- Secretory


  • These secretory elements lead into a series of ducts through which their secretion are poured into the oral cavity


Function: (read it)
produce saliva. They also secrete amylase, an enzyme that breaks down starch into glucose. In other organisms such as insects, salivary glands are often used to produce biologically important proteins like silk or glues, and fly salivary glands contain polytene chromosomes that have been useful in genetic research.


  • The major glands are located a way from oral cavity.

  • They are stimulated by olfactory, chemical, mechanical, psychological stimuli.

  • The duct system is well developed in parotid and least developed in sublingual.






Blue Histology (School of Anatomy and Human Biology - The University of Western Australia)







Blue Histology (School of Anatomy and Human Biology - The University of Western Australia)



  • Both acini are characterized by presence of myoepithelial cells which has multiple cytoplasmic processes. Their contractions help to squeeze out secretion from alveoli.

  • These cells receive autonomic innervations.

Parotid gland is purely serous

Submandibular has many serous demilunes & some serous acini

Sublingual has mucous acini + serous demilune.


Duct system

  1. Intralobular ducts = the smallest ducts.

- They are ducts that present within a lobule of the gland and surrounded by alveoli – there are two types:

  1. Intercalated ducts

They are lined by squamous to low cuboidal cells. They are open into next duct: striated
b- Striated duct

They are lined by a simple columnar epithelium that show

striation.
The basal part of the cell, plasma membrane show infoldings and mitochondria lined up these infolding.
They modify saliva by ion pumps (energy yields by mitochondria).


  1. Interlobular ducts

They arise from the union of intralobular - run between lobules – lined by high columnar surround by connective tissue septa join to form lobar duct

High columnar st. cuboidal
The lobar duct joins to form the main or major excretory duct which is lined by st.sq epith. Open into oral cavity.
The tongue

Ant. ⅔ separate from post. ⅓ by terminal sulcus .

Ant ⅔ characterized by presence of papillae.

Post. ⅓ characterized by presence of lingual tonsil give irregular nodularity

Tongue papillae = these are a coating small protrusions on the dorsal surface of ant. ⅔ of the tongue

There are three kinds

1- Filiform papillae = selender projection 2-3 mm long

Structure = it is composed of connective tissue core covered

by st. sq. epith where surface cells are Para keratinized, i.e.

they have keratin

- most numerous.

- Appear whitish due to parakeratosis

- No tast buds.
2- Fungiform papillae

- They have the shape of mushrooms.

- They appear as reddish dots on the surface of the tongue

because they have CT core rich in blood vessels

the surface epith. is non – keratinized.

They often posses tast buds on their surfaces.
3- Circumvellate papillae

- Least numerous = few and most complex.

- Largest papillae about 10 – 12

- They are present a long the terminal sulcus.

- Each papilla sunk into the mucous membrane surrounded by

deep circular trench.

- The lateral surface of the papillae have numerous taste buds.

- Serous gland von Ebnner’s gland open into bottom of trenches.

- Providing a fluid medium in which molecules dissolve to

trigger these taste impulse and which contrary washes trench

to ensure continuity of the sense of taste.
Taste buds


  • The taste buds are pale oval body situated within dark- staining epithelium.

  • They rest on the basement membrane and extend to the surface and open through a small taste pore.








Blue Histology (School of Anatomy and Human Biology - The University of Western Australia)


Filiform papillae



Fungiform papillae


Circumvallate papillae


  • There are two types of cell within the taste buds:

1. Neuroepitelial cells =

Light staining – euchromatic nucleus with long microvilli.


2.Supporting (sustentacular cells)

Dark stained – heterochromatic nuclei with long microvilli.


3. Basal calls

- New impulse penetrates and surrounds the taste buds.

- Four primary taste sensations, sweat, salty, bitter and acid sour.

They differ in region of tongue.



Fungi form + circumvalate taste buds

And there is taste bud in soft palate, glosopalatin arch, epiglottis,

posterior wall of the pharynx.


Mucosa epith + papilla

Lamina propria



Submucosa glands

Musculosa skel. muscle ext.

Int. i.e. inf.

Sup.


Vertical





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