OCB02-2023

Question 1

What are the anterior and posterior boundaries of the oral mucosa?

Answer 1

Anterior = vermillion border

Posterior = anterior pillar of fauces (palatoglossal arch)

Question 2

What areas are covered by oral mucosae?

Answer 2

Upper and lower labial mucosa and sulci

Buccal sulci and mucosa

Free and attached gingiva

Hard and soft palate

Dorsal and ventral surface of tongue

Floor of mouth

Question 3

What are the two main parts of the oral mucosa?

Answer 3

Epithelium

Lamina propria (corium)

Question 4

How do you know where the submucosa of the oral mucosa is histologically?

Answer 4

Fat and skeletal muscle (and possibly minor salivary glands) present

Question 5

What is the boundary between the mucosa and submucosa in the alimentary tract?

Answer 5

Muscularis mucosae

Question 6

What are rete pegs?

Answer 6

Extensions of epithelium into lamina propria

Question 7

What are connective tissue papillae?

Answer 7

Extensions of lamina propria between rete pegs

Question 8

What is another term for masticatory mucosa?

Answer 8

Oral mucoperiosteum

Question 9

What does the lining mucosa cover?

Answer 9

Buccal mucosa and sulci

Labial mucosa and sulci

Ventral tongue

Floor of mouth

Soft palate

Question 10

Where can you find specialised mucosa in the mouth?

Answer 10

Dorsal aspect of anterior 2/3 of tongue and parts of lateral margin of tongue

Question 11

Where is the epithelium of the oral mucosa thickest?

Answer 11

Buccal mucosa

Question 12

Where are the rete pegs of the oral mucosa longest and most slender?

Answer 12

Hard palate

Question 13

Where is the lamina propria thickest in the oral mucosa?

Answer 13

Hard palate

Question 14

Why is the lamina propria thinner at the floor of the mouth?

Answer 14

Salivary glands

Question 15

Which type of oral mucosa has no definite submucosa?

Answer 15

Masticatory mucosa/oral mucoperiosteum

Question 16

Describe masticatory mucosa.

Answer 16

Covers hard palate and attached gingiva

No definite submucosa

Lamina propria continuous with periosteum of underlying bone (tightly bound)

Question 17

What are the layers of epithelium in masticatory mucosa?

Answer 17

Stratum basale

Stratum spinosum

Stratum granulosum

Stratum corneum

Question 18

Describe the stratum basale of the masticatory mucosa.

Answer 18

Stem cells and transit amplifying cells

Single layer of short columnar/cuboidal, hyperchromatic cells

Attached to underlying lamina propria at basal lamina via hemidesmosomes

Question 19

What stain can be used to view the basal lamina/basement membrane zone?

Answer 19

PAS (periodic acid- Schiff) stain

Also electron microscopy

Question 20

Describe how the basement membrane zone.

Answer 20

Hemidesmosomes concentrate tonofilaments of basal cells and some traverse the membrane to attach to the basal lamina

Beneath basal lamina are anchoring fibrils of type VII collagen that loop between collagen fibrils of the lamina propria

Most proteins of BL made by epithelial cells

Bullous pemphigoid antigen helps anchor basal cell to BL

Question 21

How does the basal lamina appear under electron microscopy?

Answer 21

2 layers = lamina lucida (superficial) and lamina densa (deep)

Question 22

What is the function of the bullous pemphigoid antigen?

Answer 22

Helps anchor basal cells to basal lamina

Question 23

What is mucous membrane pemphigoid?

Answer 23

Autoimmune condition with antibodies targeting bullous pemphigoid antigen of the basal lamina

Weakens adhesion between epithelium and lamina propria

Formation of vesicles, bullae and blisters

Question 24

Describe the stratum spinosum of masticatory mucosa.

Answer 24

Larger cells than basal layer

Polygonal, pale-staining cells with large nuclei with nucleoli

Cells linked by desmosomes

Question 25

In keratinised masticatory mucosa, which layer of the epithelium is thickest?

Answer 25

Stratum spinosum

Question 26

Describe a desmosome.

Answer 26

Intercellular adhesion (attach adjacent cells together) Formed of cadherins which are formed by desmoglein and desmocollin

Question 27

What makes up a cadherin?

Answer 27

Desmoglein and desmocollin

Question 28

What is pemphigus?

Answer 28

Autoimmune disease with antibodies targeting desmoglein of desmosomes Breakdown of intercellular adhesion and cells pull away from each other (acantholysis) Formation of blisters

Question 29

What is acantholysis?

Answer 29

Loss of intercellular connections (desmosomes)

Question 30

The blisters in which disease break more easily and why: pemphigoid or pemphigus?

Answer 30

Pemphigus Blisters are more superficial

Question 31

Describe the stratum granulosum of masticatory mucosa?

Answer 31

Keratohyaline (basophilic) granules in cytoplasm Cells become flattened, nuclei become enlarged and elongated Start to lose nuclei and organelles

Question 32

What is keratohyaline the precursor for?

Answer 32

Filaggrin

Question 33

Describe the stratum corneum of masticatory mucosa?

Answer 33

Stains bright orange-pink with H&E Indistinguishable cells, flattened, tightly-packed with few organelles

Question 34

What are the different forms of stratum corneum in the oral mucosa?

Answer 34

Parakeratinised = nuclei preserved Orthokeratinised = nuclei lost

Question 35

What is the function of filaggrin?

Answer 35

As the cells progress from the granular to cornified layer, filaggrin forms a tight complex with loricrin and involucrin Envelopes bundles of keratin tonofilaments and merge with cell membrane of maturing cells to create the "cornified envelope" For structural integrity and waterproofing

Question 36

What colour does hyperkeratosis look?

Answer 36

White

Question 37

Under normal circumstances, is the lining mucosa keratinised?

Answer 37

No (normally non-keratinised stratified squamous epithelium)

Question 38

What are the layers of the lining mucosa epithelium?

Answer 38

Stratum basale Stratum intermedium (no granules) Stratum superficiale (no keratin)

Question 39

Why is lining mucosa more flexible and less waterproof than masticatory mucosa?

Answer 39

No keratin or cornified envelope

Question 40

Where may sebaceous glands be found in the oral cavity?

Answer 40

Lamina propria of buccal mucosa or labial mucosa

Question 41

What are Fordyce spots/granules?

Answer 41

Benign yellowish small plaques formed by coalescing of sebaceous glands of buccal or labial mucosa

Question 42

Why are the vermillion border and lips red?

Answer 42

Thin epithelium with many dilated blood vessels

Question 43

What separates the base of the tongue from the oral tongue?

Answer 43

Sulcus terminalis

Question 44

What is found anterior to the sulcus terminalis?

Answer 44

Circumvallate papillae in an inverted V-shape

Question 45

Which papillae are most abundant on the tongue?

Answer 45

Filiform papillae

Question 46

Which papillae are the least abundant on the tongue?

Answer 46

Foliate papillae

Question 47

Describe filiform papillae.

Answer 47

Thread-like projections covered with keratinised stratified squamous epithelium Usually parakeratinised Each is supported on a fibrous tissue core (lamina propria) Interspersed between zones of non-keratising stratified squamous epithelium Aid in mastication May have secondary papillae branching off

Question 48

Describe fungiform papillae.

Answer 48

Round, smooth-looking, almost mushroom-like Appear red due to highly vascularised lamina propria and thinner epithelium (than filiform) Numerous tastebuds at surface

Question 49

Describe circumvallate papillae.

Answer 49

Non-keratinising stratified squamous epithelium Surrounded by a trench which has numerous tastebuds located along its wall Many serous minor salivary glands (glands of Von Ebner) in submucosa essential for taste

Question 50

What are the glands of Von Ebner?

Answer 50

Minor exocrine serous salivary glands found in submucosa adjacent to trenches of circumvallate and foliate papillae Secrete lingual lipase Innervated by glossopharyngeal nerve (C.IX)

Question 51

Describe a tastebud briefly.

Answer 51

Rounded, modified nerve structures with pores opening onto the surface of the tongue Stain with S-100

Question 52

What non-keratinocyte cells are found in the oral epithelium?

Answer 52

Melanocytes Langerhans cells Merkel cells

Question 53

Describe a melanocyte.

Answer 53

Stellate cells with clear cytoplasm found in basal layer of epithelium Produce melanin

Question 54

Describe a Langerhans cell.

Answer 54

Cells with clear cytoplasm and lobulated nuclei Clearest in upper prickle cell layer Dendritic function

Question 55

Why does the base of the tongue have a nodular surface?

Answer 55

Lymphoid tisse

Question 56

What epithelium covers the base of the tongue?

Answer 56

Non-keratinised, stratified squamous epithelium (oropharyngeal mucosa)

Question 57

What are crypts?

Answer 57

Invaginations in surface of mucosa, lined by reticulated crypt epithelium (not stratified, loosely packed) to allow antigen passage Packed with lymphoid tissue arranged as follicles