Functions of intercalated ducts: Convey the saliva from the terminal secretory units to the striated ducts Cells of the proximal portion of these ducts.

Functions of intercalated ducts:

• Convey the saliva from the terminal secretory units to the striated ducts

• Cells of the proximal portion of these ducts show indication of secretory function

• Capable of reabsorping proteins from the lumen

• Represent a reserve of UMC which offer a degree of regeneration

• Antibacterial protein ( Lactoferrin) has been localized in these ducts.

b-Striated ductb-Striated duct::

1 -Lined by a single layer of columnar cells with numerous apical microvilli.

2 -Central nucleus.

3-Eosinophillic cytoplasm.

4- Prominent Basal striations due to : a- membrane infolding b-numerous elongated mitochondria

5- a-Cell organells ………….., b-junctional complex (apically)& desmosomes (laterally)

2

a

b

4

Apical end

Functions of the striated ducts:

1- Modify the secretion passing through them (how ?)A-Their lining cells do not reabsorb water B-Actively reabsorb Na, Cl ions C-Secret K ,HCO3 ions Thus the secretion is changed fromISOTONIC With high Na,CL and low K ions

HYPOTONIC with low Na , Cl ions and high K ions

2-Iodine concentration takes place in this duct helping in Iodine metabolism.

3-The lining cells contains:

• Kallikrein (affect H2O & electrolyte balance)

• Amylase ( transferred by these ducts from the serum to saliva)

• Lysosomes ( have antibacterial effect)

c-Excretory duct and main ductc-Excretory duct and main duct

1 -Interlobular ducts lined by tall columnar cellstall columnar cells..

2 -Interlobar ducts are lined by pseudostratified pseudostratified columnar epithelium with columnar epithelium with goblet cellsgoblet cells..

3 -Main duct is lined by stratified squamous stratified squamous epitheliumepithelium

1 2

3

Goblet cell

Function of the excretory ducts:

• Covey the secretion to the oral cavity

• Reabsorb Na, Cl & secrete K, HCO3

The ductal reabsorption of Na, Cl

exceeds

secretion of K, HCO3………leading to HYPOTONIC saliva

1

DUCT

MAIN EXCRE.DUCT EXCRETORY DUCT STRIATED DUCT INTERCALATED

Modification of primary secretion.

Passive conduit

Sec. Granules. Minor contribution in secretion

Reabsorbed from primary secretion .

Secreted in primary secretion.

Secreted. Reabsorbed

FUNCTIONS OF SALVARY GLAND DUCTS

Acinus

B- Connective tissue.B- Connective tissue.Form a capsule surrounding the gland from which septa or strands extend to subdivide the gland into

major lobes. Lobes are further subdivided into lobules. Lobe

The intercalated and Striated ducts are considered intralobular ducts.

The excretory ducts on the other hand are considered

interlobular ducts.

1 – Cells :a-Fixed C.T. cells b-Migrating cells

Fibroblasts, Plasma cells, Macrophages Mast, and Fat cells. Leukocytes.

2 -Fibers:

Reticular & collagen.

3 -Ground substances: a-Glycoproteins b-proteoglcans

B- Connective tissue elementsB- Connective tissue elements

4 -Blood supply:

Follow the excretory duct to form:

a-Dense capillary network till striated duct.

b-Less capillary loops around Intercalated Duct &Secretory portion.

c- Arteriovenous anastomoses.

5- Nerves:

*Unmyelinated axons surrounded by cytoplasmic processes of the shwann cells.

*Follow the course of the vessels forming plexus in the C.T. near the Secretory portion.

Types of human salivary glands

1 -Major salivary glands:

A- Parotid. b- sumandibular. c-sublingual.

2-Minor salivary glands:A-Labial &buccal gland. B- Palatine gland.

C- Glossopalatine gland. D-Lingual gland.

1 -Major salivary glands:A- Parotid glandA- Parotid gland

*It’s the largest salivary gland.

*Its superficial portion lies subcutaneously.

*Its deeper portion lies behind the ramus.

*Pure serous in adult& mixed in infant &old age

*Main duct Stensen’s duct.

*C.T. capsule surrounds it & sends septa to divide the gland into lobes &lobules .

*Secretes 25-30% of saliva.

*Intercalated duct longer than in the other glands.

A- Parotid glandA- Parotid gland

b- Submandibular glandb- Submandibular gland

b- Submandibular glandb- Submandibular gland

*Next in size.

*Lies in the submandibular triangle behind &

below the free border of the mylohyoid M. with

small extension above it.

*Mixed predominatly serous.

*Main duct Wharton’s duct.

*Extensive C.T. capsule.

*Secretes 60-70%of secretion.

*Straited ducts longer than those of the parotid.

C-Sublingual glandC-Sublingual gland

C-Sublingual glandC-Sublingual gland*Smallest.

*Lies between floor of the mouth &mylohyoid

muscle.

*The major gland is mixed predominantly mucous.

*The minor gland are pure mucous.

*Major-Bartholin’s duct opens near sumand.duct.

*Minor-Rivinus ducts (8-10) open in sublingual fold.

*Poorly defined C.T. capsule with prominent C.T.

septa.

*Secretes 5%or less of saliva.

Comparison between major salivary glands

The type of the gland

Parotid

Pure serous in adult

Mixed in infants & old age

Submandibular

Mixed predominant

serous

Sublingual

Mixed

Predominant

Mucous

Minor subling. (pure mucous)

Main ductsStensonWharton Bartholin

(Rivinus 8-12)

parotidsubmandibularsublingual

capsuleWell developed

Well

developed

Poorly developed

I.c.ductLong

branched

Shorter than those in parotid

Poorly developed

St . ductNumerous

Well dev.

longerPoorly developed

(lacking basal st.)

Sensory innv.

mandibularnerve

Mandibular

nerve

mandibularnerve

Blood

supply

Ext. carotid

artery

Facial & lingual

artery

Sublingual &submental

artery

Sympathatic innervation….from superior cervical ganglion by post-ganglionic fibers (for all glands)

Parasympathetic innervation:For parotid gland…..from glossopharyngeal nerve which reach the gland through otic ganglion & auriculo –temperal n.For sub-mand.&sub-ling…..from facial nerve which reach the gland through submandibular ganglion

2-Minor salivary glands:2-Minor salivary glands:

- Distributed throughout the submucosa.- Small, discrete masses.- Lack distinct capsule

- Posses numerous short ducts that open directly in the oral cavity.

- Occurance of focal accumulation of lymphocytes around their duct wall.

- Secrete high amount of IgA concentration.-Secrete 7% of saliva.

A-Labial &buccal glandA-Labial &buccal gland..

-More glands are present in the lower lip.

- They are present on the surface of the orbicularis oris muscle while in the buccal mucosa they are present on the surface & inbetween the buccinator muscle.

-Mixed gland but ultrastructurally they only show mucous cells.

- Buccal glands duct open in the third molar area & are known as molar gland.

Minor mucous glands

B- Palatine gland&B- Palatine gland& C- C- Glossopalatine glandGlossopalatine gland..

Palatine:

Pure mucous.

In Hard Palate 250 Soft Palate 100

Uvula12

Glossopalatine:

Pure mucous.

Found in the isthmus region.

Gland of hard palate

D-Lingual glandD-Lingual gland

Weber gland

Blandin-Nuhn SG

von Ebner S G

1-Blandin- Nuhn Ant. part mucous, Post. Part- mixed Open in the ventral surface 2-Von Ebner (VE) Pure serous under circumvallate& folliate papillae Wash the trough, dissolve the food, Contain digestive enzymes ( amylase &

lipase ), and protective enzymes (Peroxidase & lysozymes ).

3-Weber Pure mucous Open in the lingual crypt.

D-Lingual glandD-Lingual gland

Age changes of salivary glands

1 -Fatty degenerative change.

2 -Atrophy of a part or a whole terminal portion with its replacement by fibrous tissue (Fibrosis).

3-Accumulation of lymphocytes in the stroma.

4 -in the salivary secretion which leads to xerstomia.

5 -xerstomia leads to difficulty in eating&swallowing as well as in dental caries.

6 -Oncocyte cells in number & may form neoplasm in old people.

Young age

Old age

Fatty degenerative change.

Saliva

A-Definition: Saliva is a complex fluid produced by

the salivary glands, whose important role is maintaining the well being of the mouth.

For ex. patients with deficiency of salivary secretion experience difficulty in eating, speaking& swallowing & become prone to mucosal infections & rampant caries.

1-Protective functions: It provides a washing action that clears harmful substances in the oral cavity.

Functions of saliva:

2-Buffering action: Mucin lubricates oral tissues and forms a barrier against microbial products. Saliva maintains neutral pH in the oral cavity which prevents demineralization of enamel that would occur due to acids produced by sugar metabolizing bacteria.

3-Maintenance of tooth integrity:*Saliva is rich in calcium and phosphate ions that leads to post eruptive maturation of enamel which increases their hardness and resistance to demineralization. *It helps to protect the teeth from dental caries.

*The cleansing action of saliva and the presence of high molecular weight glycoproteins which aggregate specific strains of microorganisms reduce the concentration of substrates and number of bacteria in the oral cavity.

4-Defense: (antimicrobial action) (bacteriostatic)*Salivary IgA is an important factor in oral immune defense, together with salivary agglutinins (glycoproteins)

*IgA causes clumping of certain microorganisms thus preventing them from adhering to oral and dental surfaces.

*Other components namely histatins, lysozyme, lactoferrin and peroxidase inhibit bacterial growth.

5-Taste functions

• * It enables the pleasurable sensations of food to be experienced.

• *It permits the recognition of noxious substances.

• *Contains protein Gustin necessary for growth & maturation of taste buds

6-Digestive functions:

• Saliva has digestive enzymes as

*amylase :

carbohyderate…………Glucose &

Maltose

*Lingual lipase produced by von Ebner

Triglycerides diglycerides & fatty acids

7-Tissue repair

• Experimentally;

Clotting time …….accelerated when saliva is mixed with blood

Rate of wound contraction…..increased in presence of saliva as it contains epidermal growth factor produced by submandibular s.g in mice.

Thank you& Good luck