Introduction to Histology and Staining

Question 1

what is histology

Answer 1

microscopic study of normal cells

Question 2

what is light microscopy

Answer 2

tissue samples are illuminated by a beam of light

Question 3

what is electron microscopy

Answer 3

tissue samples are illuminated by a beam of electrons

Question 4

what does light microscopy reveal

Answer 4

basic cellular structure

Question 5

what does electron microscopy reveal

Answer 5

ultrastructure of cells

Question 6

what is the revolution for light microscopy

Answer 6

0.2 micrometres

Question 7

what is the revolution for electron microscopy

Answer 7

1 nanometer

Question 8

what version of microscopy is compatible with staining

Answer 8

light

Question 9

what are the seven stages of microscopy collection

Answer 9

specimen collection
fixation
dehydration
embedding
sectioning
staining
viewing

Question 10

what is embedding

Answer 10

embedding tissues in a hard medium in order to support tissue so it doesn’t get distorted when cut

Question 11

what is a hard tissue used in embedding of specimens

Answer 11

paraffin wax

Question 12

why are tissue samples dehydrated

Answer 12

the cells are full of water which isn’t compatible with the wax of the embedding stage

Question 13

name three types of biopsy

Answer 13

incision or punch biopsy
needle biopsy
endoscopic biopsy

Question 14

what is incision biopsy

Answer 14

used where tissues are easily available - skin and oral surfaces

Question 15

what is needle biopsy

Answer 15

used for organs or lumps below skin - imaging techniques used to guide needle

Question 16

what is endoscopic biopsy

Answer 16

flexible tube used to collect specimen

Question 17

what is fixation

Answer 17

preserves structural arrangement between cells and extracellular structures - terminates all biochemical reactions

Question 18

what are two common chemicals used in fixation

Answer 18

formaldehyde
glutaraldehyde

Question 19

how are tissues dehydrated

Answer 19

submersing the tissue in a series of graded alcohols - done in stages to prevent distortion

Question 20

as wax is not compatible with alcohol, what is the alcohol replaced with in the final stages before embedding

Answer 20

xylene

Question 21

how thick should tissue sections be when viewing

Answer 21

7 micrometres

Question 22

why are samples stained in light microscopy

Answer 22

allows for identification of different cellular structures

Question 23

why do you have to reverse the dehydration steps before staining

Answer 23

stains are not compatible with paraffin as they are aqueous to replace with water gradually

Question 24

what is the most commonly used staining technique

Answer 24

haematoxylin and eosin (H&E)

Question 25

what is haematoxylin and what does it stain

Answer 25

it is a basic dye which stains acidic structures blue/ purple

Question 26

what is eosin and what does it stain

Answer 26

acid and stains basic structures red or pink

Question 27

what is periodic acid shchiff reaction

Answer 27

PAS - stains complex carbohydrates magenta

Question 28

what is an example of complex carbohydrates

Answer 28

mucin

Question 29

what is Masson Trichrome stain

Answer 29

it stains connective tissues

Question 30

what structures are stained in masson trichrome staining

Answer 30

nuclei are blue/ purple
collagen is green/ blue
cytoplasm/ muscle and red blood cells stain red

Question 31

what is immunohistochemistry

Answer 31

uses antibody specificity for antigen - the antibody is usually conjugated with a colour indicated

Question 32

what does alcian blue stain

Answer 32

mucin and cartilage blue

Question 33

what does can gieson stain

Answer 33

collagen red
nuclei, erythrocytes and cytoplasm yellow

Question 34

what does reticulin stain

Answer 34

reticulin fibres which is a component of connective tissue blue/black