Week 10 - Histology of Oral Mucosa Regional Variation Flashcards
What are the regional variations of oral mucosa
What are the different types of oral mucosa
Lining mucosa
Masticatory mucosa
Specialized mucosa
What is lining mucosa
Found in areas of the oral cavity that is not subjected to the same mechanical stresses as masticatory mucosa.
Where is lining mucosa found (3)
- lips
-labial and buccal mucosa - floor of the mouth
What is masticatory mucosa
This is the specialized type of oral mucosa that covers the gingiva and the hard palate. This type of mucosa is adapted to withstand the forces generated during chewing (mastication) and protects the underlying structures such as the alveolar bone and teeth.
Where is masticatory mucosa found
- gingiva
- hard palate
what is the example of specialized mucosa
dorsum of the tongue (contains papillae)
Describe the characteristics of labial mucosa
Lining Mucosa
- Non-keratinized
- Lines the inner surface of the lip
- Many mucous glands in the submucosa
- Wide and short papillae
- Connective tissues bind to the underlying orbicularis muscle (muscle of the lip)
What is the muscle of the lip called
orbicularis muscle
Describe the characteristics of the floor of the mouth
Lining Mucosa
- Non-keratinized, thin
- Numerous short papillae and elastic fibers
- Extensive vascular supply (rich blood supply) - hence has a rapid drug absorption
- Irregular and thin submucosa (this can be seen because the floor of the mouth is very thin)
Describe the characteristics of the vermillion zone
Lining mucosa
- Skin on the outside side and the labial mucosa on inner side of the lips
- Mucocutaneous junction connects skin with mucosa
- Translucent keratinized epithelium
- Numerous long narrow papillae
- Capillary loops in the papillae are close to surface - also rich blood supply
- Mucosa firmly attached to the underlying muscle
Describe the characteristics of gingiva
Masticatory Mucosa
- Para-keratinized - may contain nuclei but they are small and shrunken
- Prominent epithelial rete ridges (toughs)
- Slender and long connective tissue papillae
- There is no submucosa, and the lamina propria is directly attached to periosteum (mucoperiosteum)
- Fibers run perpendicular to the surface causing stippling - loss of stippling means that the gingiva is inflamed - there is no stippling if there’s gingivitis
What is stippling
refers to the textured appearance of the gum such like the dimpled surface surface of an orange peel (this is a sign of healthy gingiva)
Describe the characteristics of the hard palate
- Ortho-keratinized/para-keratinized and thick
- No submucosa in the central region
- Lamina propria directly binds to bone (mucoperiosteum) - no submucosa
- Long papillae
- moderately vascular
- Minor mucous gland posteriorly aspect
Describe the characteristics of the dorsum of the tongue
Specialized mucosa
- Functionally masticatory mucosa but it has taste buds
- Anterior 2/3 is covered by numerous papillae
What are the 4 different types of papillae seen on the tongue
- Filiform
- Fungiform
- Circumvallate
- Foliate
Describe filiform papillae
- Thin and cone shaped
- There are the most number of these papillae however they are very small and hard to see
- They are responsible for giving the tongue its texture and are responsible for sensation of touch
- Consist of a central core of lamina propria with smaller papillae branching from it
Describe fungiform papillae
- Isolated, elevated mushroom shaped
- Covered by thin epithelium which may be keratinized or nonkeratinized
- Taste buds may be found
Describe circumvallate papillae
- An anatomical landmark of the tongue as it is a V shaped sulcus terminal which divides the tongue into anterior 2/3 and posterior 1/3
- Located anterior to sulcus terminalis
- Easily seen on the tongue
- Arranged in V shaped
- Covered by non-keratinized epithelium
- Surrounded by a trench like feature
- Taste buds seen in the internal wall of the trench
- Small serous glands (von Ebner) open into the base of the trench. These glands secrete amylase. This digestive enzyme breaks down food.
Describe foliate papillae
- Present at the side of the posterior part of the tongue
- Non-keratinized surface
- May contain taste buds
What are taste buds
- Special chemoreceptive organs
- These structures are involved in detecting the 5 elements of taste perceptions: salty, sour, bitter, sweet and umami
- Barrel/onion shaped
Where are taste buds found
Located within the epithelium of walls of:
- circumvallate papillae
- fungiform papillae
- mucosa of the soft palate
What are the 2 types of cells in the taste buds
- supporting cell
- taste (gustatory cell)
What are supporting cells
cells which form an outer envelope for the taste bud
What are taste (gustatory) cell
chemoreceptors that send information to the brain - they are attached to nerve fibres
What are the 3 major salivary glands
- They are located outside the oral cavity
- All Bilateral glands
1. Parotid gland
2. Submandibular gland
3. Sublingual gland
What is the structure of a salivary gland
- Parenchyma of the gland consists of a series of ducts ending in series of secretory end pieces
- Similar to a bunch of grapes where the stalks of the grapes represents the ducts and the grapes represent the secretory end pieces
What is the structure of different ducts and end pieces
Collecting duct —> Striated Ducts —> Intercalated Ducts —> Terminal end pieces
What are secretory units composed of (3)
- Ductal system
- Terminal acini
- Myoepithelial Cells
What is the ductal system
The duct system transport the secreted substance from the secretory cells to the site of release. It may consist of different types of ducts.
What are the 4 components of the Ductal system
- Intercalated Duct (smallest and most distal)
- Striated Duct
- Collecting duct
- Excretory Duct (largest and only one of these)
They lead from 1 to 4
What is terminal acini
Acini = means a rounded secretory unit
They are the end portion of the secretory ducts where the actual secretion of the glandular product occurs.
What are the different types of terminal acini
- Serous Acinus Cells
- Mucous acinus cells
Describe serious acinus cells
- Wedge shaped
- Nucleus is located in the basal region of the acinar cell
- The cell contains dense secretory granules
- Appears more dark pink in colour due to the secretory granules and nucleuses
Where are serous acinus cells commonly found
parotid gland
Describe serous demilune
- These are mucous secreting glands
- They in the shape of a half-moon
- These demilune cells secrete the proteins that contain the enzyme lysozyme, which degrades the cell walls of bacteria - causing destruction of bacteria
- Located at the distal end of mucous secretory unit of certain salivary glands
What does serous demilune secrete
Proteins which contains the enzyme lysozyme which degrades the cell walls of bacteria - causing destruction of bacteria
Where are serous demilune most commonly found
sublingual salivary gland and minor salivary glands
Describe mucous acinar cells
- Triangular or pyramidal in shape
- Possess flattened nucleus
- Contain numerous mucous containing granules
- Need special stain to see mucin granules
- Appear pale under H&E (Hematoxylin and Eosin staining) section
- Appears light pink under microscope
Describe myoepithelial cells
- Muscle
- Branched stellate (spider like) cells
- Wrap around portions of the duct system and serve to squeeze secretion from the acinus and associated duct system
Where are mixed: Sero-mucous cells found
submandibular
Describe the parotid gland
- Largest of the salivary glands
- Enclosed within well defined capsule
- Acini are serous, and occasionally mucous
- Serious cells stain deeply with H&E
- Connective tissue contains blood vessels, nerves and collecting ducts
What type of acini is found in parotid gland
serous
Describe the submandibular gland
- Second largest gland
- Mixed sero-mucinous (both serous acini and mucous acini, both light and dark pink colour)
- Well formed capsule
- Nuclei in the basal part of the cell
What type of acini is in the submandibular gland
mixed: Sero-mucinous
Describe the sublingual gland
- Predominantly mucous secreting (predominantly light pink in colour)
- Consists of pale staining mucous cells
- Duct system is less developed
- No striated duct evident - produces sodium rich saliva (more than what is produced in other glands
What type of acini is found in the sublingual gland
mucous
Describe minor salivary glands
- These glands are predominantly mucous secreting cells (light pink)
- They have continuous secretory activity
- Produce about 10% of the total saliva
- Release saliva through numerous small ducts
Where are minor salivary glands located
- Lips (labial)
- Cheeks (buccal)
- Hard and soft palate
- Tongue (lingual)
- Sublingual
- Floor of the mouth
What are some clinical consideration of salivary glands
- Dry mouth (xerostomia )
- Mucoceles - when the minor salivary glands rupture (due to biting your lip) and the saliva will extrude out into the mucosa
- Sialolithiasis
- Sialosis
- Neoplasms
- Stafney’s bone cavity
