Intro To Histology Flashcards

1
Q

What is histology?

A

The microscopic study of normal cells and tissues

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2
Q

What is disease typically associated with in relation to tissue structure and function?

A

Usually associated with disruption of normal tissue structure and function

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3
Q

That is pathology?

A

The microscopic study of disease cells and tissues

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4
Q

What is dysplasia of squamous cells?

A

Refers to abnormalities in squamous epithelium, the epithelium being the layer of cells that lines the cavity or surface in the body

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5
Q

What are examples of physical and chemical insults that induce alterations in tissue architecture?

A
  • Infection
  • Extreme heat/cold
  • Cuts or fractures
  • Poison/drugs
  • Genetic and congenital changes
  • Aging, wear and tear
  • Cancer
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6
Q

What is required to visualise tissue structure?

A

Microscopes as cells are too small to see by the naked eye

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7
Q

What 2 microscopes are used to look at tissue samples?

A
  • Light microscope

- Electron microscope

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8
Q

What does a light microscope reveal of the tissue?

A

Basic cellular structure

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9
Q

What does an electron microscope reveal of the tissue?

A

Ultrastructure - structures only able to see through electron microscope

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10
Q

Which microscope is most commonly used for routine histopathology?

A

Light microscope

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11
Q

What are the 7 steps for making thin tissue samples for viewing?

A
  1. Specimen collection
  2. Fixation
  3. Dehydration
  4. Embedding
  5. Sectioning
  6. Staining
  7. Viewing
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12
Q

What are the 3 types of biopsy?

A
  • Incision or punch biopsy
  • Needle biopsy
  • Endoscopic biopsy
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13
Q

What is an incision or punch biopsy of?

A

Skin/oral surfaces

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14
Q

What is a needle biopsy of?

A

Organs or lumps below the skin

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15
Q

What is an endoscopic biopsy?

A

Flexible tube with light and camera. Cutting tools can be used to collect tissue specimens

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16
Q

What imaging techniques are often used to guide biopsy?

A

X-ray, MRI

17
Q

What does fixation of tissue do?

A
  • Preserves the structural arrangement between cells and extracellular components
  • Terminates all biochemical reactions and so prevents tissue decomposition
18
Q

What are 2 common fixatives?

A
  • Formaldehyde

- Glutaraldehyde

19
Q

What is dehydration of tissue to produce a tissue sample?

A
  • Water is removed from tissue using a series of graded alcohols
  • Water is removed gradually to prevent distortion
20
Q

Why does tissue need to be dehydrated for tissue sampling?

A

Since paraffin in immiscible with water, the main constituent of tissue, Samples need to be dehydrated by progressively more concentrated ethanol baths. This if followed by a clearing agent, usually xylene, to remove the ethanol. Finally molten paraffin wax infiltrates the sample and replaces the xylene

21
Q

What materials are most commonly used for embedding?

A
  • Resins

- Paraffin wax

22
Q

Why does tissues for sample need to be embedded?

A
  • Thin tissue sections are required for microscopy BUT most tissues are delicate and easily distorted, so tissues must be supported to allow thin sections to be cut
23
Q

Paraffin is not compatible with alcohol, so what is alcohol replaced with to allow embedding to occur?

A

Xylene

24
Q

What must the characteristics of tissue sections be?

A
  • Thin and flat
  • Ideally a single layer of cells
  • Should be transparent
25
Q

What is a microtome?

A
  • What embedded specimens are sectioned using

- A tool used to cut extremely thin slices of material

26
Q

What can tissue sectioning in different areas of the tissue cause?

A

Can make a big difference to tissue architecture

27
Q

Why do most cells need some sort of staining?

A
  • Most of them are colourless and transparent
  • Staining makes cells and their components more visible
  • Allows the identifications of different cell and tissue features
28
Q

What is the composition of most LM stains?

A
  • Aqueous
29
Q

Some stains for tissue examination are not compatible with paraffin, what needs to be done to fix this?

A
  • Reversal of dehydration steps to remove paraffin wax and replace with water
30
Q

What is the most commonly used stain?

A

Haematoxylin and Eosin (H&E)

31
Q

What is haematoxylin?

A

A basic dye, which stains acidic structures (such as nucleic acids) BLUE/PURPLE

32
Q

What is eosin?

A

An acidic dye that stains basic structures (such as cytoplasmic proteins) RED or PINK

33
Q

What does periodic acid-Schiff reaction stain?

A

Complex carbohydrates MAGENTA (such as mucins, produced by goblet cells, brush borders and basement membranes)

34
Q

What does Masson trichrome stain?

A
  • Stains connective tissues
  • Nuclei and other basophilic structures stain BLUE
  • Collagen stains GREEN/BLUE
  • Cytoplasm, muscle, red blood cells ad keratin stain RED
35
Q

What is immunohistochemistry?

A

Refers to the process of detecting antigens in cells of a tissue section via antigen reveal. This is carried out by exploiting the principle of antibodies binding specifically to antigens in biological tissues

36
Q

How do you make permanent mounts of tissue samples?

A
  • Stained sections are dehydrated once again to replace water with xylene
  • Mounting medium and a coverslip seal to protect sections