Intro to Histology Flashcards

1
Q

Light microscopy

A
  • pass visible light through a specimen

- lens allow both magnification & resolution of details within the tissue specimen

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2
Q

what is resolution?

A

-ability to distinguish two close but distinct points

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3
Q

Steps to prepare tissue for imaging (6)

A

1) fixation
2) dehydration
3) embedding
4) sectioning
5) removal of resin/parafin
6) staining

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4
Q

what is fixation?

A
  • stabilizes structures & prevents degradation

- use alcohol, paraformaldehyde

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5
Q

what is dehydration?

A

the gradual removal of H20 in preparation of tissues

  • allows the auditioning of embedding w/ a hardening agent
  • use a series of baths with progressively increasing alcohol proportions
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6
Q

what is embedding?

A
  • infiltrate the tissue w/ harder substance to make it easy to cut into thin sections (resin/parafin)
  • keeps tissue from shriveling up
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7
Q

What is sectioning?

A

-tissue is sectioned using rotary microtome so that the tissue slice is translucent and can be seen through w/ the microscope

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8
Q

what is straining?

A

-the introduction of contrasts to tissue that is otherwise transparent

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9
Q

what is cryo-alternative?

A
  • used for immediate evaluation of tissues & immune-fluorescence techniques
  • fast/easy alternative since doesn’t require dehydration or embedding
  • uses deep freezing
  • but less stable than parafin/resin embedded sections
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10
Q

benefits of Cry-alternative process? negatives?

A

1) rapid freezing reduces ice crystal formation & preserves cell structure

2) tissue not as stable/ doesn’t last as long
- exspensive

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11
Q

What are cell smears?

A
  • blood or bone marrow epithelial cells which are not sectioned, spread from source directly onto the glass sheet
  • are often fixed in alcohol (either bath or sprayed)
  • are processed for staining immediately
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12
Q

What is Hematoxylin and Eosin (H&E)?

A

hematoxylin: a basic dye that stains acidic components of cells blue (nuclei, RER, DNA/ribosomes)
eosin: an acidic dye that stains the basic components of cells a reddish-pink (cytoplasm, bone matri, proteins)

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13
Q

How H& E used to ID midoticallly active cells?

A
  • euchromatin is DNA in use, it is spread out/diffused and less stained since open
  • heterochromatin (compact) is condensed/ replicating cells and stains darker
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14
Q

Periodic acid-Schiff (PAS) staining

A
  • used for carbohydrates, polysaccharides (glycogen) and gut/liver sections
  • pink/magenta color gives very clear lines
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15
Q

H&E vs H& PAS?

A
  • H& PAS gives much clearer/distinct lines since are lighting up polysaccharides
  • mixed with hematoxylin to label nuclei blue
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16
Q

orecin staining?

A

used to stain elastic fibers dark brown/purple

-example is the elastic component in the walls of arteries or in the matrix of elastic cartilage

17
Q

Osmium tetroxide?

A

-stains lipids & myelin dark black

18
Q

Oil red O?

A
  • stains neutral lipids a red-orange color in unfixed frozen sections
  • since fixation dissolves lipids
19
Q

Toluidine blue staining

A
  • high affinity for acid tissues-stains nucleic acids blue & polysaccharides purple
  • good for chromosomes
20
Q

metal impregnation?

A
  • silver is most commonly used to demonstrate reticular fibers/neurons
  • tissue bathed in metal solutions and metal will attach to specific cell components
21
Q

nissl stain?

A
  • selective staining, uses an aniline stain to label extra-nuclear RNA granules
  • nucleic acid staining method use don nervous tissue sections
  • binds (-) charge on nucleic acid
  • marks ER as well
22
Q

what is vital staining? (4 types)

A
  • the uptake of dyes by the cell
    1) trypan blue
    2) Wright (Giemsa stain)
    3) Neutral Red
    4) Janus Green
23
Q

Trypan blue?

A
  • rapidly engulfed by macrophages and can be used to delineate liver cells
  • DISTINGUISHES alive/dead cells
24
Q

Giemsa staining (Wright)

A

mixture of methylene blue, eosin and azure Blue

  • attaches to DNA
  • stains blood/bone marrow smears & parasites
25
neutral red
- incorporated by live cells into their lysosomes - red when protonated - colorless and permeable when unprotonated - accumulate in acidic lysosomes where protonation is occurring
26
Janus green?
- changes color w/ different amounts of oxygen - green= oxidized - colorless= before oxidation - accumulates in oxidative env. of mitochondria
27
What is immunohistochemistry (IHC) or immunocytochemistry (ICC)? Process?
- use of antibodies to label proteins of interest 1) antibodies either directly labeled or need secondary antibody 2) use fluorescent dyes/enzymes that enable a colorimetric rxt
28
IHC vs ICC difference?
``` -IHC= uses tissue sections ICC= staining of isolated blood cells or cultured intact cells ```
29
Two types of electron microscopy?
1) Scanning electron microscope (SEM) | 2) Transmission electron microscope (TEM)
30
What is transmission electron microscope?
(TEM) - form of electron microscopy - electrons passed THROUGH specimen - great for INTERNAL detail - focused on magnetic lenses - image formed on fluroescent screen then photoed - better resolution than SEM
31
What is scanning electron microscope?
(SEM) - electrons passed round the specimen - provides detailed study of the SURFACE - lower resolution than TEM