Histological Methods

Question 1

Classify skin and its tissue type

Answer 1

organ; epithelial + conn.

Question 2

Classify fascia and its tissue type

Answer 2

tissue; connective

Question 3

Classify tendons and its tissue type

Answer 3

dense, regular conn. tissue; connective

Question 4

Classify aponeurosis and its tissue type

Answer 4

tissue; connective

Question 5

Classify bone and its tissue type

Answer 5

organ/tissue; variety of connective

Question 6

Classify blood vessels and its tissue type

Answer 6

organ/tissue; epithelial/connective/muscular

Question 7

Classify nerves and its tissue type

Answer 7

tissue/organ/system; nervous

Question 8

Classify muscle and its tissue type

Answer 8

organ/tissue; muscular

Question 9

What is a plain of section

Answer 9

• the part of the specimen you’re looking at
• how 3D structures may appear when thin sectioned in different ways
• essentially different point of views of the same structure

Question 10

What is the resolution power of an electron microscope

Answer 10

200nm

Question 11

1cm= (mm)

Answer 11

10

Question 12

1mm=(micrometres)

Answer 12

1000

Question 13

1micrometre=(nm)

Answer 13

1000

Question 14

1nm=(A)

Answer 14

10

Question 15

Which methods of fixation are used in light microscopy

Answer 15

perfusion, immersion

Question 16

Which methods of fixation are used in e microscopy

Answer 16

perfusion

Question 17

What is perfusion

Answer 17

pumping fixatives into blood supply of animal to freeze tissues
*faster than immersion

Question 18

What is immersion

Answer 18

anesthetizing the animal, taking a specific organ, plopping it into fix which penetrates it and freezes the tissue

Question 19

Which fixatives are used in light microscopy

Answer 19

• formalin
• mercuric chloride
• picric acid
• Bouin’s Fluid

Question 20

Which fixative is used in e microscopy

Answer 20

glutaraldehyde

Question 21

Why is perfusion preferable in e microscopy

Answer 21

since we’re looking at finer details we need to fixate the specimen faster

Question 22

List the 11 steps of preparing a slide in terms of light microscopy

Answer 22

1. fixation
2. dehydration (using increasing concentrations of ethanol to get rid of water)
3. clearing (xylene-paraffin solvent to get rid of ethanol)
4. infiltration (mixing xylene with paraffin wax to make substance more liquidy)
5. embedding (100% paraffin, wax block)
6. sectioning (microtome, slice = 5 microns)
7. mounting(glass slide)
8. removal of paraffin(using xylene)
9. rehydration(using ethanol, decreasing concentrations, get back to H2O)
10. staining (hematoxylin/eosin)
11. light microscopy

Question 23

Why do we use increasing concentrations of ethanol to remove water instead of using 100% right away

Answer 23

osmotic pressure would be too high, causing tissue to burst

Question 24

List the steps of preparing a slide in terms of electron microscopy

Answer 24

1. fixation
2. dehydration (same as light)
3. clearing(propelyne glycol-epoxy solvent to get rid of ethanol)
4. infilitration(propelyne glycol and plastic)
5. embedding(100% plastic block)
6. sectioning(ultramicrotome, slice =5nm)
7. mounting(metal grid)
8. staining(lead citrate &/or histochemical rxns)
9. transmission electron microscopy

Question 25

Why does e microscopy use plastic

Answer 25

it's harder so we can make thinner slices, e are shot at it and it won't show up in the images

Question 26

What is hematoxylin

Answer 26

stain used in light microscopy, basic, blue/purple, stains nucleus and acidic structures

Question 27

What is eosin

Answer 27

stain used in light microscopy, acidic, pink, stains cytoplasm+collagen

Question 28

What are characteristics of lead citrate

Answer 28

stain used in e microscopy, no specific colour, sticks to proteins, stains membranes with various affinity, doesn't stain cytoplasm

Question 29

What are basophilic structures

Answer 29

those containing nucleic acids like ribosomes and the nucleus and regions in cytoplasm that are rich in RNA

Question 30

What are acidophilic (eosinophilic) structures

Answer 30

intra/extracellular protein, most of cytoplasm

Question 31

Do structures have to be acidic or basic to be named basophilic or acidophilic

Answer 31

no, naming is based on affinity to dyes

Question 32

What is an electron lucent structure

Answer 32

a "light space" that is created when electrons pass through the grid/slide/specimen and don't hit anything

Question 33

What is an electron dense structure

Answer 33

a dark space created from electrons hitting off the lead citrate and bouncing away

Question 34

What is the magnification of a light microscope

Answer 34

1000x

Question 35

What is the magnification of an electron microscope

Answer 35

160 000x