Week 10 - Histology of Oral Mucosa Flashcards

1
Q

What is histology

A

the study of the microscopic anatomy of cell and tissues of plants and animals

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2
Q

What are different tissues of the oral cavity

A
  • Oral mucosa
  • Teeth (enamel, dentine and pulp)
  • Periodontal tissues (alveolar bone, periodontal ligament, cementum and gingiva)
  • Salivary glands (major and minor salivary glands)
  • Bone
  • muscles
  • nerves
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3
Q

What are the 3 main parts of the oral mucosa

A
  1. Oral epithelium
  2. Lamina propria (connective tissue)
  3. Submucosa
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4
Q

What type of cell comprises oral epithelium

A

stratified squamous

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5
Q

What are the 2 types of oral epithelium

A
  • Keratinized
  • Non-keratinized
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6
Q

What are the cell layers in keratinized oral epithelium

A
  • stratum corneum (cornified cell layer)
  • stratum granulosum (granular cell layer)
  • stratum spinosum (prickle cell layer)
  • stratum Basal
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7
Q

What are the main characteristics of the stratum corneum (cornified cell layer)

A
  • nuclei and organelles disintegrated
  • cells filled with keratin
  • desmosomes disappear to allow cells to be shed away
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8
Q

What are the main characteristics of stratum granulosum

A

3-5 cell layers above the stratum spinosum
* Contain large number of keratohyalin granules

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9
Q

What are keratohyalin granules

A

Keratohyaline granules help to form the matrix of keratin fibres of the stratum corneum layer - they help bind the keratin fibers of the stratum corneum layer

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10
Q

What are the characteristics of stratum spinosum

A
  • several cell layers thick
    -Contains several tonofilaments (fine proteins), they also bundle to form a tonofibril
  • Desmosomes increase in number and become more obvious - therefore gives a prickly appearance
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11
Q

What are the main characteristics of stratum basale

A
  • Single layer of cuboidal cells
  • Adjacent to lamina propria
  • Almost constant mitosis producing daughter cells where 1 become the superior cell layers, while the other remains as a stem cell
  • Cells are connected by desmosomes, hemidesmosomes, intermediate, tight and gap junctions-
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12
Q

What are the cell junctions found in the stratum basale (5)

A
  • desmosomes
  • hemidesmosomes
  • Intermediate junctions (adherents junctions)
  • gap junctions
  • tight junctions
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13
Q

What are desmosomes

A
  • provides cell to cell adhesion (adjacent cells)
  • Provides adhesion through intermediate filaments (type of protein)
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14
Q

What are hemidesmosomes

A
  • Stud like structures found in keratinocytes that attach to the extracellular matrix
  • Attaches cells to the basal lamina (where as desmosomes attach to adjacent cells)
  • Uses intermediate filaments to create adhesion
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15
Q

What are intermediate junctions (adherents junctions)

A
  • These are cell to cell adhesions and cell to extra cellular adhesions
  • Uses actin filaments to provide adhesion (actin filaments are the same as intermediate filaments but they a smaller)
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16
Q

What are gap junctions

A
  • They are communicating junctions which allow the direct chemical communication between adjacent cell cytoplasm through diffusion
  • This occurs through a special type of protein
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17
Q

What are tight junctions

A

Main function is to prevent leakage of solutes and water and seals between the epithelial cells

18
Q

What are the 2 types of keratinized oral epithelium

A
  • ortho-keratinized
  • para-keratinized
19
Q

What is ortho-keratized oral epithelium

A

keratinized oral epithelium which has no nuclei or organelles

20
Q

What is para-keratinized oral epithelium

A

Keratinized oral epithelium where the cells may retain nuclei but they are small and shrunken.

21
Q

Where is para-keratinized oral epithelium found

A

gingiva

22
Q

What is non-keratinized oral epithelium

A
  • Cells are non-keratinized at the surface
  • No keratohyalin granules
  • More organelles in the surface layer
23
Q

What are the cell layers of non-keratinized oral epithelium

A
  1. Superficial cell layer (stratum superficial)
  2. Intermediate Layer (stratum intermedium)
  3. Basal cell layer
24
Q

What are some non keratinocyte cells

A

Melanocyte
langerhan cells
merkel cells

25
Q

What are melanocytes

A
  • derived from neural crest cells
  • located in the basal cell layer
  • Melanin is produced and packaged into vesicles - melanosomes
  • Difference in skin colour reflects the activity and size of melanosomes, not the number of cells
26
Q

What are langerhans cells

A
  • Located in the layers above the basal layer
  • Derived from bone marrow precursors
  • Immune function
  • Responsible for anti-tumour immunity, graft rejection and contact hypersensitivity reactions
27
Q

What are merkel cells

A
  • Found in the basal cell layer
  • Closely apposed to nerve fibers
  • It is a specialized neural pressure sensitive receptor cell
  • Responds to touch sensation
28
Q

What are key differences between keratinized and non keratinized epithelium

A
  • Different cell layers
  • Non-keratinized don’t have keratohyalin granules
  • the top layer of non-keratinised has nuclei in its cells
29
Q

What are the 2 layers of the lamina propria

A
  • papillary layer
  • reticular layer
30
Q

What is the papillary layer of the lamina propria

A

-upward projections of connective tissue = connective tissue papillae

-downward projections of epithelium = rete ridges or rete pegs

31
Q

What are connective tissue papillae

A

upward projections of connective tissue

32
Q

What are rete ridges or rete pegs

A

downward projections of epithelium

33
Q

What is the reticular layer of the lamina propria

A

It is located below the papillary layer which consists of more of a matrix

34
Q

What is the epithelial connective tissue interface/ basement membrane

A

Layer of cells in between the oral epithelium and lamina propria which helps connects these tissues

35
Q

What does the epithelial-connective tissue interface/ basement membrane consist of

A

Lamina Lucida = immediately under the epithelium

Lamina dense = electron dense and composed of network of type IV collagen

36
Q

What is the submucosa

A
  • Deepest layer
    -A layer of loose fatty glandular tissue
  • Contains vessels and nerves
  • Separates the oral mucosa form underlying bone or muscle
37
Q

Where is submucosa found

A

Present in cheeks, lips and part of hard palate - the palate is hard because it doesn’t have a lot of submucosa - on the other hand the soft palate is abundant with submucosa

38
Q

Where is the submucosa not found

A

not found in the gingiva

39
Q

What is the oral mucoperiosteum

A
  • The oral mucosa is directly attached to the underlying bone - there is no submucosa layer
  • It provides a firm inelastic attachment
40
Q

Where is the oral mucoperiosteum found

A

Present in gingiva and parts of the hard palate