Histology Lecture 3a -- Oral Mucosas

Question 1

Describe the epithelium of the skin on the face

Answer 1

Stratified squamous epithelium, keratinized and shows hair follicles, sebaceous glands, and sweat glands

Question 2

Layer beneath the epithelium of the skin

Answer 2

Connective tissue layer called the dermis

Question 3

2 layers of the dermis of the skin

Answer 3

Papillary layer

Reticular layer

Question 4

Describe the organization of the papillary layer

Answer 4

Interdigitated with the rete pegs of the epithelium

Question 5

Layer contained in the skin epidermis

Answer 5

Stratum granulosum layer with basophilic keratohyalin granules

Question 6

Define stratum corneum of the skin

Answer 6

Dead cell layer that is orthokeratinized

Question 7

Define orthokeratinized

Answer 7

The usual or true form of keratinization

Question 8

Define the red border of lip

Answer 8

A transitional region from dry to wet surface epithelium (dry skin-type epithelium becomes the wet oral mucous membrane or oral mucosa)

Question 9

What layer is the lamina propria of the oral mucosa continous with at the level of the lips

Answer 9

The dermis of the skin

Question 10

Describe the keratinization of the lips

Answer 10

Epithelium is partially keratinized, so keratinized near the skin, but non-keratinizaed near the oral mucosa

The keratinized layer is thin, making the epithelium translucent

Question 11

Describe the dermis/lamina propria of the lips

Answer 11

Rete pegs are very deep and the vessel-containing papillae of the lamina propria extend very close to the lip surface

Question 12

Describe the anatomical location of the oral mucosa

Answer 12

Entire inside of the mouth except for the gingiva and the dorsal surface of the tongue

Question 13

Describe the epithelium of the oral mucosa

Answer 13

Stratified squamous epithelium, nonkeratinized

Surface cells of the epithelium are squamou but contain nuclei and desquamate as living cells into the oral cavity

Question 14

Describe the lamina propria of the oral mucosa

Answer 14

Very vascular (reason for deep red color of mucosa)

Question 15

Layer beneath the lamina propria of the oral mucosa and its contents

Answer 15

Submucosa, which has small glands that constitute the minor salivary glands (may be serous, mucous or mixed)

Question 16

Define the anatomical location of gingiva

Answer 16

gums surrounding the teeth and cover the entire hard palate

Question 17

Define the mucogingival junction

Answer 17

Where the oral mucosa nad gingiva meet at a visible line in the mouth

Question 18

Describe the epithelium of the gingiva

Answer 18

Modification of the stratified squamous epithelium. Has a stratum germanitavum and a stratum spinosum layer, but no stratum granulosum. Spinosum cells flatten and become keratinized, but do not die. They retain their nuclei until they desquamate.

Question 19

Define parakeratinization

Answer 19

Type of keratinization found in the gingiva wherein the spinosum cells of the epithelium flatten and become keratinized, but do not die. Instead, they retain their nuclei (thin, flattened and not obvious) until they desquamate. Form a thick regular layer that stains deeply eosinophilic

Question 20

What layer is the submucosa of the gingiva and hard palate continuous with?

Answer 20

Periosteum lining the alveolar bone or the palatine process of the maxilla (therefore the gingiva does not move freely over the bone)

Question 21

Define the junctional epithelium of the gingiva

Answer 21

Gingiva reflects onto the tooth surface and the cells become modified for attachment to the tooth surface

Question 22

What does the formation of the junctional epithelium of the gingiva involve?

Answer 22

Formation of hemidesmosomal attachments to the calcified surface of the tooth (can be to either the enamel or the cementum)

Question 23

What is the only seal separating the “dirty (bacteria, etc)” oral cavity from the “inside” lamina propria and blood vessels supplying the gingiva?

Answer 23

Hemidesmosomal attachments

Question 24

2 subdivisions of the palate

Answer 24

Hard palate

Soft palate

Question 25

What underlies the mucosa of the hard palate?

Answer 25

Bone

Question 26

What underlies the mucosa of the soft palate?

Answer 26

Skeletal muscle

Question 27

Describe the mucosa of the palate

Answer 27

Masticatory mucosa similar to that of the gingival (i.e. with a stratified squamous parakeratinized epithlium). Reflects around the soft elastic palate and the uvula where it is a stratified squamous nonkeratinizing epithelium, to become respiratory epithelium (pseudostratified ciliated columnar) on the nasal side of the palate.

Question 28

How is the mucosa attached to the palatine bone in the hard palate region?

Answer 28

By a mucoperiosteum

Question 29

Where can salivary glands be found in the palate?

Answer 29

Laterally in the mucosa

Question 30

Differentiate between the two portions of the tongue

Answer 30

* Free portion = covered entirely by epithelium * Attached portion = epithelial lining continues with the oral mucosa covering the floor of the mouth

Question 31

Describe the musculature of the tongue

Answer 31

Striated muscle with fibres that run in all directions and are: * Intrinsic = origin and insertion from the connective tissue within the tongue * Extrinsic = origin within the tongue, but an insertion outside the tongue (i.e. larynx)

Question 32

Describe the contents between the muscle fibres in the tongue

Answer 32

Connective tissue containing fat and minor salivary glands that open by ducts to the epithelial covered surface of the tongue

Question 33

What is located between the floor of the mouth and the tongue

Answer 33

Sublingual gland, a major salivary gland

Question 34

Describe the epithelium of the dorsal surface of the tongue

Answer 34

Partially keratinized, modified in the form of papillae (projections from the surface)

Question 35

4 types of tongue papillae

Answer 35

1. Filiform (threadlike) papillae 2. Fungiform (mushroom shaped) papillae 3. Foliate papillae 4. Circumvallate papillae

Question 36

Tastes that utilize G-protein coupled membrane receptor pathways

Answer 36

* Bitter * Sweet * Umami

Question 37

Tastes that utilize ion channels

Answer 37

* Sour (acid) = proton channel * Salt = sodium channel

Question 38

Most numberous type of papillae on the tongue

Answer 38

Filiform papillae

Question 39

Reason for the tongue's whitish velvety appearance and feel

Answer 39

Filiform papillae (keratinization of the epithelium)

Question 40

Disrtibution of filiform papillae on the tongue

Answer 40

Fine ros on either side of the central line bisecting the tongue

Question 41

Describe the histology of filiform papillae

Answer 41

Cup-shaped or pointed projections of epithelial cells that are usually keratinized on the outside, but not on the inside. Keratinization takes place from a stratum granulosum layer where the granules are eosinophilic.

Question 42

What do the eosinophilic granules of the stratum granulosum layer in the filiform papillae resemble?

Answer 42

Resemble the trichohyalin granules seen in the internal root sheath of the fair follicle

Question 43

Describe the filiform papillae in animals such as the cat

Answer 43

* Very well-developed * Keratinized surface forms a sharp-ended structure with the sharp tip directed posteriorly = raspy feel to tongue and provides pockets that fill with fluid (lap up liquids)

Question 44

Describe the distribution of fungiform papillae on the tongue

Answer 44

Between the filiform papillare as small ret dots and are more numerous on the sides and tip of the tongue

Question 45

Describe the histology of fungiform papillae (5)

Answer 45

* Mushroom-shaped * Lined by a stratified squamous epithelium (non-keratinized) * Taste buds on top * Core = lamina propria (primary connective tissue papilla) * Smaller interdigitated papillae with epithelial papillae = LP close to surface --\> red

Question 46

Define foliate papillae

Answer 46

Folds in the mucosa (rather than actual papillae)

Question 47

Location of foliate papillae

Answer 47

Predominantly in the posteriolateral portions of the tongue

Question 48

Describe the development of foliate papillae from birth

Answer 48

Taste buds are present only in the newborn and soon degenerate, as do the papillae

Question 49

What empties into the base of the furrows of foliate papillae

Answer 49

Von Ebner glands

Question 50

How is the tongue divided postero-anteriorly?

Answer 50

Anterior two thirds divided from the posterior third by a V-shaped line of papilae, the lingual V.

Question 51

Describe the form of the lingual V

Answer 51

The apex of the V is directed posteriorly and the arms of the V are formed by 8 - 12 very large circumvallate papillae

Question 52

What is behind the apex of the lingual V

Answer 52

A blind invagination called the foramen caecum

Question 53

What is the foramen caecum?

Answer 53

The rudiment of the thyroglossal duct, which is the origin of the epithelial invagination from which the thyroid gland developed

Question 54

Describe the general structure of circumvallate papillae

Answer 54

* Large structures with a large primary papilla and numberous secondary connective tissue papillae * Extend just above the surface of the tongue, surroudned by deep crypts

Question 55

Describe the walls of the crypts surrounding circumallate papillae

Answer 55

The side walls are formed by other tongue papillae on the outside and the smooth walls of the circumvallate papillae themselves, both of which have numerous taste buds in the epithelium.

Question 56

How do the taste buds of circumvalalte papillae open into the crypt lumen?

Answer 56

Taste pores

Question 57

Describe how the taste buds in the walls of the circumvallate papillae are stimulates

Answer 57

Substances dissolved in the saliva enter the crypt space and stimulate the sensory cells

Question 58

What happens to the fluid in the crypts of the circumvallate papillae

Answer 58

Continuous replacement by serous secretions delivered to the bottom of the crypt by way of numerous ducts from serous glands found under the circumvallate papillae

Question 59

Location of Von Ebner glands

Answer 59

Under the circumvallate papillae

Question 60

Histological location of taste buds

Answer 60

From the basal lamina through the epithelium to the surface

Question 61

What forms the taste pore of taste buds?

Answer 61

Squamous epithelial cells

Question 62

4 types of cells in the taste bud

Answer 62

* Columnar * Type I dark supporting cells * Type II light neuroepithelial cells * Type III intermediate cells * Basal cell (type IV)

Question 63

Location of the cells types I to III in the taste bud

Answer 63

From the base of the taste bud, with their microvilli opening into the taste pore

Question 64

Location of the nuclei of the columnar taste bud cells

Answer 64

Central regions

Question 65

Location of Type IV basal cells in taste bud

Answer 65

Peripheral to the columnar cells and does not reach the taste pore

Question 66

Function of Type IV basal cells in taste bud

Answer 66

Stem cell that renews the other cells

Question 67

Turnover of taste bud cells

Answer 67

10 days

Question 68

Descirbe the support cells for the taste buds

Answer 68

* Secretory * Contain secretion granules with a content that resembles the amorphous material surrounding the microvilli in the taste pore

Question 69

Number of neuroepithelial cells per taste bud

Answer 69

4 - 20 per taste bud

Question 70

Location of neuroepithelial cells of the taste bud

Answer 70

Dispersed throughout, between the supporting cells

Question 71

Contents of neuroepithelial cells of the taste bud

Answer 71

Vesicles that resemble synaptic vesicles, which are related to the free nerve endings that enter the taste bud through the basal lamina

Question 72

Describe the stimulation of taste buds

Answer 72

Substances dissolved in the saliva stimulate the sensory hairs (microvilli) and the impulse produced is conducted to the nerve endings

Question 73

Function of Von Ebner glands

Answer 73

Removal of the stimulatory substances from the taste buds