Saliva 3 - salivary biology 1

Question 1

What are the major pairs of salivary glands?

Answer 1

• parotid
• sub-mandibular
• sub-lingual

Question 2

What are the key features of salivary glands?

Answer 2

• ducts
• acini

Question 3

What are the 3 types of salivary ducts?

Answer 3

intercalated ducts < striated ducts < secretory ducts

Question 4

Describe the path of salivary secretion

Answer 4

• principally starts in the acini, acini feed and produce the primary salivary secretion
• secretion travels intercalated ducts
• these ducts then feed into the striated ducts
• the striated ducts modify the saliva
• this then going through the secretory ducts, which get larger as they head towards mouth
• the secretion then goes through the larger ducts, into the papillae and out into the mouth

Question 5

What is the histological structure of the acini?

Answer 5

pyramidal cells around a central lumen

Question 6

What is the histological structure of the intercalated ducts?

Answer 6

very small simple cuboidal cells

Question 7

What is the histological structure of the striated ducts?

Answer 7

massively folded basal membrane on the cells that line it, increases surface area for exchange

big cells, play a significant role in the saliva process - modify the saliva

Question 8

What is the histological structure of the secretory ducts?

Answer 8

much larger ducts, as we get toward the mouth, the walls become increasingly stratified- multiple layers of cells lining the walls

Question 9

What ducts have a role in modifying the primary secretion of saliva?

Answer 9

the striated ducts

Question 10

Describe the pyramidal cells of the acini

Answer 10

wide basal margin, narrow luminal margin

polarised cells - peripheral nucleus

Question 11

What do the acini produce?

Answer 11

primary secretion

Question 12

What are the different types of acini?

Answer 12

• serous
• mucous
• mucous with serous demilunes

Question 13

What is an example of a gland that is predominantly serous?

Answer 13

parotid

Question 14

What is an example of a gland that is predominantly mucous?

Answer 14

sublingual

Question 15

What is an example of a gland that is mixed (serous and mucous)?

Answer 15

sub-mandibular

Question 16

What do serous acini cells look like?

Answer 16

• prominent, clear basal nucleus
• basophilic RER - manufacturing secretory cells
• granular appearance

Question 17

What do mucous acini cells look like?

Answer 17

• pale cytoplasm - mucins lost or not easily stained
• flattened basal nucleus
• many large mucin granules

Question 18

Why are the nuclei of mucous acinar cells flattened?

Answer 18

lots of large mucin granules - cause the nucleus to be flattened and pushed to the basal aspect of the cell

Question 19

Why do mucous acinar cells look very pale in comparison to serous acinar cells?

Answer 19

mucous acinar cells full of mucin granules, which are either removed during processing of the section or don’t pick up the stain - cells look pale on microscope

Question 20

What are mucous acinar cells with serous demilunes?

Answer 20

• mucous acinus capped by serous cells
• serous cells discharge via intercellular canaliculi between the mucous cells
• artifactual ?

Question 21

What are myoepithelial cells?

Answer 21

central cell body with process sticking out, enclosing acini

Question 22

Where are myoepithelial cells found?

Answer 22

on acini and intercalated ducts

Question 23

What is the function of myoepithlial cells?

Answer 23

• contractile elements
• “squeeze” acinus - may assist secretion
• regulate duct lumen diameter (of the intercalated duct)

Question 24

What do the cells of the intercalated ducts look like?

Answer 24

• low cuboidal cells
• large central nucleus
• difficult to see in routine wax sections
• in cross section, intercalated ducts look like a circle of cells around a tiny central lumen

Question 25

What do intercalated ducts do?

Answer 25

quite passive, don’t have anything that’ll modify saliva etc., saliva produced by the acini and it passes down the intercalated ducts

• myoepithelial cells around them, can squeezed to push the saliva into the next stage (the striated ducts)

Question 26

Are striated ducts present in all salivary glands?

Answer 26

no, not present in the sublingual glands

Question 27

What do the straited ducts do?

Answer 27

a active modification of the primary saliva

Question 28

What do the cells of the straited ducts look like?

Answer 28

central nucleus due to massive basal membrane folding (nucleus cannot get any more basal than it is)

Question 29

In terms of cell size, compare the intercalated and striated ducts

Answer 29

straited ducts have very big cells aground them compared to the intercalated ducts, but still have quite a small lumen

Question 30

Why is there basal membrane folding in the cells of the striated ducts?

Answer 30

to increase surface area for exchange with surrounding tissues, to cause changes in the saliva, lots of membrane pumps taking ions in and out of both sides of the cell (cells also have lots of mitochondria for this)

Question 31

What do the secretory ducts look like?

Answer 31

• large lumen
• initially pseudostratified and then become stratified near termination - merges with stratified squamous oral epithelium

Question 32

What is the relative size of secretory ducts, their walls and their lumen?

Answer 32

• secretory ducts largest in diameter, and get larger as they reach exit into mouth
• large lumen, wall relatively small despite being multilayered