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Histology > Exam1Lec1Microscopy > Flashcards

Exam1Lec1Microscopy Flashcards

1
Q

Wht are the steps of preparing a sample to be looked at under a microscope?

will test in this

A
  1. Fixation
  2. Dehydration
  3. Clearing
  4. embedding
  5. sectioning
  6. mounting
  7. staining
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2
Q

Fixation

A

preservation so it stabalizes the protein to prevent degradation

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3
Q

What fixation chemical method is used for LM?

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A

Formaldehyde solution to react with amine group

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4
Q

What fixation chemical method is used for EM?

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A

Glutaraldehyde solution that cross links proteins and uses osmium tetroxide that preserves membranes

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5
Q

Dehydration

A

get water out by bathing tissue in a progressive series of ethanol + water mixture up to 100% ethanol so you can embedd it

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6
Q

Clearing

A

100% ethanol with the tissue is replaced by xylene and makes the tissue transparent

this allows paraffin to penetrate the tissue, xylene is miscible w/ the embedding medium which makes the tissue clear

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7
Q

embedding

A

embeds the tisue in a hardend mold for easy slicing in 2 types waxy substance. Paraffin and epoxy resins (used when tissue is cleared with plastic solvents)

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8
Q

What are the steps of using paraffin wax to embedd?

A
  1. Paraffin is melted to 58-60 degrees c
  2. Tissue is placed in the melted wax, heat causes xylene to evaporate
  3. paraffin cools and hardens
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9
Q

Sectioning

A

Slicing hardenned tissue using a microtime to thin it out so light can pass through

cuts 6 microns for LM and .06 for EM (thinner b/c is an electron beam, aka more powerful) know this

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10
Q

Mounting

A

tissue sections are mounted on on glass slide (LM) or wire grid (EM)

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11
Q

Staining

A

Staining tissue with hematoxylin (H) in water and Eosin (E)

HE stain for LM

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12
Q

What are the steps for section staining?

A
  1. Dissolve paraffin wax with xylene
  2. re-hydrate section through a series of alcohols stained with H-stain in water
  3. de-hydrate section through a series of alchols stained with eosin (E-stain)
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13
Q

What is the most common dyes used for tissue staining?

A

Combination of H&E

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14
Q

What is the ultimate goal for preparation of tissues for microscopic examination?

A

Enable transmission of a light or election beam through tissue to produce a visible image

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15
Q

Enable transmission of a light or election beam through tissue to produce a visible image it requires slicing of tissue into thin sectios and attaching the sections to what?

A

A glass slide (LM) or wire grid (EM)

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16
Q

Eosin is and ____ dye and carries a net ____ charge

A

acidic, negative

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17
Q

Eosin reacts with a ____ charge and you get a ____ colored stain

A

positve, pink

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18
Q

Hematoxylin is an overall ____ dye and carries and net ___ charge.

A

basic, positive

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19
Q

Hematoxylin reacts with a ____ charge and you get a ____ colored stain

A

negative, blue

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20
Q

Hematoxylin stains what types of organelles?

A

Nucleus/ nucleic acids
Ex: RER bc ribosomes have a lot of nucleic acids

rna rich organelles (ribosomes + rER)

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21
Q

RER is in the ___ ____ so it stains____?

A

basal membrane, blue

basals

22
Q

The lumen and secreatory vesicles are part of the ____ group so it stains ____.

A

apical, pink

23
Q

After fixation of cells and tissues, the ____ of their components differs from living tissues.

A

chemical composition

24
Q

After fixation, what remains in the tissue sample?

A

Large insoluble molecules or macromolecular complexes

fat gets washed out

25
Q

What is the only organelle that you can see on a light level?

A

Nucleus

you can get an impression of other organelles with staining

26
Q

Often a viewed ____ unit is also a ____ unit.

A

structural, functional

27
Q

Some large and small molecules are generally lost during tissue prep due to what?

A

the use of organic solvents during tissue preparation

28
Q

We can characterize a cell by ____ and ____.

A

nucleus, shape

29
Q

You are looking at an ____ through fixation and staining.

A

artifact

30
Q

____ is an example of distortion.

A

Shrinkage

31
Q

What are artifacts of prep?

A

Collection of distortions caused by prep procedures (shrinkage, artificial spaces, loss of molecules, etc.)

32
Q

Shrinkage causes

A

fixation, dehydration (in ethanol), heating (in melted paraffin during clearing)

33
Q

What are artificial spaces?

A

Holes b/w cells + ec components. This is caused by shrinkage and loss of molecules due to chemicals used in tissue prep.

34
Q

Some ____ components don’t stain well with HE so they stain w/ Heavy metals

A

neuro

35
Q

What you see through eyepiece is an accumulation of ____ and ____ of eyepiece

A

objective, magnification

36
Q

What is the maximal resolving power of the light microscope?

A

0.2 microns

37
Q

What is the magnification for LM?

A

1000 to 1,500 x

38
Q

What is resolving power?

A

How far apart they have to be to resolve as 2 points/separate objects

(the smallest t distance b /w 2 particles at which they can be seen as sep objects)

resolving to a certain light is based in the WL of light compared to the WL of beam

39
Q

Microscopy resolution has to do picture ____ and they closer they get together the ____ it is to resolve them as 2 points.

A

clarity, harder

quality of image depends on the resolving power.

40
Q

What is confocal microscopy used for?

A

Immunifluorescece and uses laser light. The beam is finer so you get finer resolution.

41
Q

What is the resolving power for EM?

A

0.1 nanometers, but in practice 3nm

has very high resolution

42
Q

The high resoolving power (resolution) for EM allows for magnification up to ____ times for isolated molecules and for very thin tissue sections ____.

A

400,000, 120,000

43
Q

True or False, EM has a fluorescent screen where you see fluorescene and not light

A

TRUE

44
Q

For EM, the beam passes through a condenser that is made of ____ to focus beams.

A

magnets

45
Q

Which microscope is used to see atoms?

A

Ultra voltage TEM

46
Q

For TDM, it passes electron beam ____ specimen.

A

through

47
Q

For SCM, it ____ beam off specimen.

A

bounce

48
Q

What are specialized techniques used to localize specific subtances/structures in cells and tissue sections?

A

Enzyme histochemistry, immunocytochemistry, and autoradiography

49
Q

What is the light microsope composed of?

A

Light source, condenser lens, objective lens, occular lens, and mechanical stage for supporting specimen.

50
Q

What distinguishes TEM vs LM?

A

It has the same componenets but it uses an electron beans as an “illuminating” beam, magnets for lens, and a fluorescent screen to visualize the structure.

Histology (39 decks)

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