Prac 1: Oral Cavity, Pharynx & Oesophagus

Question 1

What types of glands are present on the external surface of the LIP? What type of secretions do these glands produce?

Answer 1

Sebaceous Gland

Epithelium: Keratinized stratified squamous epithelium

Question 2

What types of glands are present on the INTERNAL surface of the LIP? What type of secretions do these glands produce?

Answer 2

Seromucous & salivary glands (moisten mouth, initiate digestion of food and help protect teeth from decay)
Epithelium: non keratinized stratified squamous epithelium

Question 3

The region that is devoid of hair and glands?

What type of muscle is present at the region of the lip?

Answer 3

Vermillion Border
Simple squamous Epithelium (slightly less keratinised)
Muscle type: Skeletal muscle- orbicularis oris - sphincter of the mouth

Question 4

How are the skeletal muscle fibres arranged within the tongue?

Answer 4

They are arranged at right angles- they are the intrinsic muscles of the tongue and include the:

• superior longitudinal
• vertical and transverse muscles
• inferior longitudinal muscle

Question 5

Name the various papillae of the tongue

Which contain taste buds?

Answer 5

Curcumvillate papillae: have Von Ebners glands underneath and secrete lingual lipase. 1/2 taste buds
Folliate papillae: posterolateral margins of the tongue, contain 1/4 taste buds
Fungiform papillae: mushroom like, everywhere. Contain 1/4 of the taste buds
Filliform Papillae- NON gustatory, act to increase friction in the mouth

Question 6

Lingual Papillae- what type of papillae are these? What type of glands release their secretions into these crypts? What is the name of these specific glands and what do they produce?

Answer 6

Lingual papillae are circumvillate papillae (gustatory). beneath them are Von Ebners glands which release their secretions into the crypts formed on either side of the papillae.
Von Ebners glands are serous secreting glands which produce lingual lipase (breaks down fats)

Question 7

How can you tell the difference between the anterior 2/3 and posterior 1/3 of the tongue?

Answer 7

Anterior 2/3: lingual papillae and skeletal muscle fibres in 3 directions. stratified squamous non keratinised epithelium.
Posterior 1/3: No papillae, lots of primary and secondary lymphoid follicles present (MALT) as well as salivary glands

Question 8

What is the primary stage of tooth development? Explain

Answer 8

CAP PHASE:

Mesenchyme adjacent to the enamel organ (formed from the dental lamina) condenses to form the dental papillae

Question 9

What is the second stage of tooth development?

Answer 9

BELL PHASE:
The enamel organ develops a layer of ameloblasts (produce enamel). The dental papilla develops a layer of odontoblasts (secrete dentine)
The formation of the dentine & enamel has begun between the two epithelial layers!!

Question 10

What is the third stage of tooth development?

Answer 10

ERRUPTION PHASE

Elongation of the tooth

Question 11

Which cells are responsible for the production of the enamel? From which of the three embryonic tissues do they arise from?

Answer 11

Ameloblasts produce enamel and they arise from the ectoderm

Question 12

Which cells are responsible for the production of dentin? which embryonic tissue does this arise from?

Answer 12

Odontoblasts produce dentin!! From embryonic mesenchyme (mesoderm)

Question 13

What is the dental Lamina?

Answer 13

During the BUD Stage, the dental lamina is the intiial downgrowth of ectoderm that will form the enamel organs. There are 4 of these which appear at about six eeks

Question 14

What is the Stellate Reticulum?

Answer 14

The stellate reticulum is located within the enamel organ (bell stage, may be present but less developed in the cap stage). The cells of the stellate reticulum are star shaped and have many cellular processes interconnected with one another to form a network within the enamel organ. It plays a role in maintaining tooth shape & protecting underlying dental tissue

Question 15

Permanent Tooth Bud

Answer 15

Primary/decidious teeth begin to form between the 6th and 8th weeks, and permanent teeth begin to form in the 20th week. Permanent teeth develop when the dental lamina develops posteriorly & gives rise to a bud (side branch) adjacent to the deciduous one.

Question 16

Name two enzymes found in saliva

Answer 16

Amylase (breaks down starch) & lingual lipase (breaks down fats)

Question 17

What are the three cell types found in a secretory acinus?

Answer 17

Serous cells
Mucous cells
Myoepithelial cells- basement of the acinus

Question 18

Describe a SEROUS cell

Answer 18

A serous cell generally has a round nucleus which can be either in the centre of the cell or pushed to the basal region. The cytoplasm stains positively in H&E sections.

Question 19

Describe a MUCOUS cell. Why dont they stain well with H&E?

Answer 19

Mucous cells have a flattened nucleus that is pushed to the basal region of the cell by an accumulation of mucin which does not stain well with H&E.
Mucin has a large water carrying capacity & also has less RER than serous cells, plus it has lots of GLYCOGEN (carbohydrate that doesn’t stain) and for these reasons it stains much lighter with H&E.

Question 20

What does the parotid gland secrete?

Answer 20

100% serous

Question 21

What does submandibular gland secrete?

Answer 21

80% serous 20% mucous

Question 22

What does the sublingual gland secrete?

Answer 22

80% mucous, 20% serous

Question 23

In what form are the serous components of the sublingual gland? Can this type of structure be found in any of the other salivary glands?

Answer 23

The sublingual gland is mainly mucous with small amounts of serous components, and these are usually seen as serous demilunes (cap in the shape of a half moon). Small numbers of serous demilunes will also be present in the submandibular gland.

Question 24

What is the pathway of drainage from the Acini?

Answer 24

Acini drain from their central lumen to intercalated ducts to striated ducts (intralobular ducts) and eventually to interlobular ducts. Striated ducts are more commonly seen in serous glands, but be aware that they are not present in the pancreas.

Question 25

What is the ultrastructure of a striated duct?

Answer 25

Striated ducts are lined by simple tall cuboidal to low columnar epithelium, with a centrally positioned nuclei. They are an intralobular duct with basal & lateral cell membrane infoldings which create these striations – the function of these is to increase the surface area occupied by pumps involved in ion & fluid transport. The abundant mitochondria are arranged in between these infoldings & work to reabsorb sodium from the secretions (secretes potassium & bicarbonate to create a hypotonic alkaline secretion).

Question 26


What type of epithelium lines each of the three regions of the pharynx?

Answer 26

Nasopharynx is lined by respiratory epithelium – pseudostratified, ciliated columnar epithelium with goblet cells. The Oropharynx & laryngopharynx are lined by a stratified squamous keratinized epithelium.

Question 27

What is a mucosa?

Answer 27

A mucosa is a mucous secreting membrane consisting of epithelium, and underlying lamina propria & in the digestive tract, a layer of smooth muscle (muscularis mucosa)

Question 28

How many Palatine Tonsils are there?
What type of epithelium is present
Crypts?

Answer 28

2 palatine tonsils
Stratified squamous epithelium
10-20 cryps

Question 29

How many Lingual Tonsils are there?
What type of epithelium is present
Crypts?

Answer 29

Numerous
Stratified squamous
1 crypt

Question 30

How many Pharyngeal Tonsils are there?
What type of epithelium is present
Crypts?

Answer 30

1 pharyneal tonsil
Respiratory epithelium- pseudostratified columnar with goblet cells
Folds which may resemble crypts

Question 31

Name and describe the layers of the oesophagus

Answer 31

Tunica mucosa- non keratinised stratified squamous epithelium
Lamina Propria- LCT and a layer of smooth muscle called the Muscularis mucosa
Tunica submucosa- or the tunica muscularis and depending on where the section was taken:
Tunica adventitia or tunica serosa

Question 32

What is the orientation of the muscularis mucosa (part of the tunica mucosa)

Answer 32

Inner longitudinal
Middle circular
Outer Longitudinal

** the smooth muscle of the muscularis mucosa is usually described as circular in the rest of the GIT.

Question 33

What is the orientation of muscle in the muscularis externa? (tunica muscularis)

Answer 33

An inner circular and outer longitudinal layer. This can be both smooth and skeletal muscle. As you move distally, the tunica muscularis becomes thicker and more regular. In the proximal 1/3 of the oesophagus there is only skeletal muscle, in the middle there is both smooth and skeletal and in the distal third there is only smooth muscle.

Question 34

In what layer are oesophageal glands found? Where long the length of the oesophagus are they found? Do these glands produce a serous or mucous secretion?

Answer 34

The submucosal glands found in the oesophagus are entirely mucous secreting. They are present most commonly within the proximal 1/3 of the oesophagus and at the junction with the stomach.