Lab 3 - epithelial tissue: structural and functional analysis

Question 1

MGPY

Answer 1

methyl green (MG) is specific stain for DNA staining it greenish blue whily pyronin (PY) stains RNA pink

staining around the nucleus due to mRNA (pink) and there will also be some staining in the cytoplasm (pink) from free ribosomes)

Question 2

H and E stain colours

Answer 2

basic = pink 
acidic = purple

Question 3

Fixatives

Answer 3

preserve nucleic acids in a state suitable for staining, do not give very good preservation of general structure

Question 4

Role of acinar (exocrine) cells of the pancrea

Answer 4

to secrete digestive enzymes into the GI tract

Question 5

What organelles are inside acinar cells

Answer 5

Ribosomes (rER)
Golgi body (package and also to send out the apical pathway)
Mitchondira
Many zymogen granules at the apical region of the cell

Question 6

Distribution of DNA and RNA in the acinar cells

Answer 6

DNA = present only in the nucleus 
RNA = present in the nucleolus, also present in free ribosomes and polyribosomes, as well as rER

Question 7

MGPY stain and apical regions

Answer 7

staining will be absent from apical regions as this is where the zymogen granules are located, which is protein, and therefore the MGPY stain leaves a ‘clear area’

Question 8

Zymogen granule location

Answer 8

generally clustered apically for secretion into the lumen of the duct

Question 9

H&E and acinar cell

Answer 9

Pink in cytoplasm, purple nucleus and purple border due to nuclei basally

Question 10

MGPY and acinar cell

Answer 10

Doesnt stain symogens
Blue nucleus
Pink cytoplasm

RNA mainly in the cytoplasm being translated at rER which is basal

Question 11

Toluidine blue and acinar cell

Answer 11

Zymogen granules stained deep blue

Question 12

Amylase

Answer 12

a major secretatory protein that is stored in pancreatic zymogen granules for secretions

Question 13

rER in acinar cells

Answer 13

makes the proteolytic enzymes

Question 14

golgi in acinar cells

Answer 14

packages proteolytic enzymes into vesicles

Question 15

zymogen granules in acinar cells

Answer 15

they are released into ducts

Question 16

If tissues are stained with heavy metals…

Answer 16

contrast will increase

Question 17

TEM

Answer 17

very useful for gaining information about cellular ultrastructure to the molecular level

Question 18

Function of the duct

Answer 18

the duct carries away the digestive enzymes from the acinar cells where they are produced, to be released into the duodenum of the small intestine

Pancreatic duct cells are also able to secrete bicarbonate to neutralise acidic contents that enter the duodenum from the stomach

Question 19

Endocrine role of prancrea

Answer 19

secretes insulin and glucagon into the bloodstream

Question 20

Simple squamous …

Answer 20

flattened soma, squashed but bluging nuclus

thin for diffusion so would be found in the lining of a blood vessel

Question 21

Cuboidal epithelial

Answer 21

square shaped cell, centrally placed nucleus

lining a duct, for structure

Question 22

Tight junctions

Answer 22

prevent the unwanted transfer of substances to and from the lumen of the vessel and between cells

Question 23

Junctional complexes

Answer 23

to allow for parallel connections between adjacent cells

zonula adherens
desmosomes
Tight junctions
TAD

Question 24

Capillary

Answer 24

simple squmous

only tight junctions to not let out blood

Question 25

Lumen of the duct

Answer 25

Microvilli inside
Simple cuboidal
ZOnula adherens, desmosomes and tight junctions

Question 26

Microvilli function

Answer 26

increase surface area for absorption/secretion and it is found in the small intestine, in the nephron

Question 27

CIlia function

Answer 27

move substances on apical surface and it is found in the respiratory tract, reproductive system

Question 28

Microvilli features

Answer 28

0.5-1 microm in length
parallel bundles of actin microfilaments which insert into the terminal web of the cytoskeleton which are anchored perierally to the zonula adherens

Question 29

Cilia features

Answer 29

motile or non-motile (for sensory infor)
up to 10 microm in length - half the length of the cell
each cilium is surrounded by a plasma membrane and contains a central core - the axoneme. this consists of 20 microtubules arranged with one central doublet and 9 peripheral doublets. these are linked by proteins called nexin. Each microtubule has arms made of the protein dynein
Dynein catalyses the conversion of ATP to ADP results in bending of the doublets to create a wave like motion

Question 30

Two ways you could distinguish microvilli and cilia

Answer 30

size relative to the rest of the cell

different structure visible in the EM images i.e. the anchorings of the structures

Question 31

Anchoring of cilia and microvilli

Answer 31

cilia = well anchored below the plasma membrane

microvilli = anchored quire superficially on the plasma membrane

Question 32

Cilia are only present on

Answer 32

pseudostratified epithelia

Question 33

esophagus =

Answer 33

stratified sqaumous epithelia

Question 34

trachea =

Answer 34

pseudostratidied ciliated (columnar) epithelium

Question 35

nucleus stains - H&E, MGPY and toluidine blue

Answer 35

1 - purple (dark)
2- blue/green
3 - N/A unstained