OCB02-2023 Flashcards

1
Q

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

A

Anterior = vermillion border

Posterior = anterior pillar of fauces (palatoglossal arch)

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2
Q

What areas are covered by oral mucosae?

A

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

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3
Q

What are the two main parts of the oral mucosa?

A

Epithelium

Lamina propria (corium)

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4
Q

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

A

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

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5
Q

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

A

Muscularis mucosae

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6
Q

What are rete pegs?

A

Extensions of epithelium into lamina propria

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7
Q

What are connective tissue papillae?

A

Extensions of lamina propria between rete pegs

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8
Q

What is another term for masticatory mucosa?

A

Oral mucoperiosteum

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9
Q

What does the lining mucosa cover?

A

Buccal mucosa and sulci

Labial mucosa and sulci

Ventral tongue

Floor of mouth

Soft palate

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10
Q

Where can you find specialised mucosa in the mouth?

A

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

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11
Q

Where is the epithelium of the oral mucosa thickest?

A

Buccal mucosa

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12
Q

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

A

Hard palate

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13
Q

Where is the lamina propria thickest in the oral mucosa?

A

Hard palate

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14
Q

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

A

Salivary glands

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15
Q

Which type of oral mucosa has no definite submucosa?

A

Masticatory mucosa/oral mucoperiosteum

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16
Q

Describe masticatory mucosa.

A

Covers hard palate and attached gingiva

No definite submucosa

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

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17
Q

What are the layers of epithelium in masticatory mucosa?

A

Stratum basale

Stratum spinosum

Stratum granulosum

Stratum corneum

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18
Q

Describe the stratum basale of the masticatory mucosa.

A

Stem cells and transit amplifying cells

Single layer of short columnar/cuboidal, hyperchromatic cells

Attached to underlying lamina propria at basal lamina via hemidesmosomes

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19
Q

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

A

PAS (periodic acid- Schiff) stain

Also electron microscopy

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20
Q

Describe how the basement membrane zone.

A

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

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21
Q

How does the basal lamina appear under electron microscopy?

A

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

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22
Q

What is the function of the bullous pemphigoid antigen?

A

Helps anchor basal cells to basal lamina

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23
Q

What is mucous membrane pemphigoid?

A

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

24
Q

Describe the stratum spinosum of masticatory mucosa.

A

Larger cells than basal layer

Polygonal, pale-staining cells with large nuclei with nucleoli

Cells linked by desmosomes

25
Q

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

A

Stratum spinosum

26
Q

Describe a desmosome.

A

Intercellular adhesion (attach adjacent cells together)

Formed of cadherins which are formed by desmoglein and desmocollin

27
Q

What makes up a cadherin?

A

Desmoglein and desmocollin

28
Q

What is pemphigus?

A

Autoimmune disease with antibodies targeting desmoglein of desmosomes

Breakdown of intercellular adhesion and cells pull away from each other (acantholysis)

Formation of blisters

29
Q

What is acantholysis?

A

Loss of intercellular connections (desmosomes)

30
Q

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

A

Pemphigus

Blisters are more superficial

31
Q

Describe the stratum granulosum of masticatory mucosa?

A

Keratohyaline (basophilic) granules in cytoplasm

Cells become flattened, nuclei become enlarged and elongated

Start to lose nuclei and organelles

32
Q

What is keratohyaline the precursor for?

A

Filaggrin

33
Q

Describe the stratum corneum of masticatory mucosa?

A

Stains bright orange-pink with H&E

Indistinguishable cells, flattened, tightly-packed with few organelles

34
Q

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

A

Parakeratinised = nuclei preserved

Orthokeratinised = nuclei lost

35
Q

What is the function of filaggrin?

A

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

36
Q

What colour does hyperkeratosis look?

A

White

37
Q

Under normal circumstances, is the lining mucosa keratinised?

A

No (normally non-keratinised stratified squamous epithelium)

38
Q

What are the layers of the lining mucosa epithelium?

A

Stratum basale

Stratum intermedium (no granules)

Stratum superficiale (no keratin)

39
Q

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

A

No keratin or cornified envelope

40
Q

Where may sebaceous glands be found in the oral cavity?

A

Lamina propria of buccal mucosa or labial mucosa

41
Q

What are Fordyce spots/granules?

A

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

42
Q

Why are the vermillion border and lips red?

A

Thin epithelium with many dilated blood vessels

43
Q

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

A

Sulcus terminalis

44
Q

What is found anterior to the sulcus terminalis?

A

Circumvallate papillae in an inverted V-shape

45
Q

Which papillae are most abundant on the tongue?

A

Filiform papillae

46
Q

Which papillae are the least abundant on the tongue?

A

Foliate papillae

47
Q

Describe filiform papillae.

A

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

48
Q

Describe fungiform papillae.

A

Round, smooth-looking, almost mushroom-like

Appear red due to highly vascularised lamina propria and thinner epithelium (than filiform)

Numerous tastebuds at surface

49
Q

Describe circumvallate papillae.

A

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

50
Q

What are the glands of Von Ebner?

A

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)

51
Q

Describe a tastebud briefly.

A

Rounded, modified nerve structures with pores opening onto the surface of the tongue

Stain with S-100

52
Q

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

A

Melanocytes

Langerhans cells

Merkel cells

53
Q

Describe a melanocyte.

A

Stellate cells with clear cytoplasm found in basal layer of epithelium

Produce melanin

54
Q

Describe a Langerhans cell.

A

Cells with clear cytoplasm and lobulated nuclei

Clearest in upper prickle cell layer

Dendritic function

55
Q

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

A

Lymphoid tisse

56
Q

What epithelium covers the base of the tongue?

A

Non-keratinised, stratified squamous epithelium (oropharyngeal mucosa)

57
Q

What are crypts?

A

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