Lecture 1.2: Histology Flashcards

1
Q

What is histology?

A

It is the study of the microscopic structure of tissues.

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2
Q

Why is it necessary to preserve fresh tissue? (4)

A

To prevent putrifaction

To preserve proteins

To maintain structure

To preserve nucleic acids

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3
Q

Why is it difficult to cut thin sections of fresh tissue? How to combat this issue?

A

Fresh tissue is soft and will lose its integrity as the microtome blade passes through it

Fixation process
Embedding
Cryopreservation

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4
Q

Which methods allow for effective sectioning of tissues?

A

Cyropreservation (freezing)

Embedding in a solid medium such as wax/ plastic

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5
Q

What is the process of Embedding?

A

1) The biopsy must first be fixed (e.g. formaldehyde)
2) Ethanol (70-100%) used to dehydrate the biopsy
3) Xylene/ Toluene used for clearing
4) Then the biopsy can be embedded into wax (at 56 degrees Celsius)

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6
Q

On which component of cells to fixatives act?

A

Proteins generally

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7
Q

Name 3 common fixatives

A

Alcohol

Formaldehyde

Glutaraldehyde

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8
Q

Most common dehydrating agent?

A

Alcohol

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9
Q

Most commonly used basic dye? What does it stain?

A

Haematoxylin (dyes purple)

It stains nucleic acids (DNA, RNA)

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10
Q

Most commonly used acidic dye? What does it stain?

A

Eosin (dyes pink/red)

It stains proteins

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11
Q

Periodic Acid Schiff (PAS)

A

Dyes a deep red/magenta
Stains mucin, glycogen, complex carbohydrates and glycoproteins

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12
Q

Which stain is most effective at discriminating connective tissue structure when combines with cross-polar microscopy?

A

Sirius Red

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13
Q

Which dye most effectively stains connective muscle and tissue?

A

Masson’s trichrome

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14
Q

Which dye most effectively stains glycoprotiens?

A

PAS

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15
Q

Which dye(s) most effectively stains general tissue organisation?

A

Haemotoxylin and Eosin

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16
Q

Which dye(s) most effectively stains different immune cells?

A

Giemsa (or Wright’s)

17
Q

Which dye most effectively stains reticular proteins?

A

Silver Stain

18
Q

Which dye(s) most effectively stains elastic fibres?

A

Van Gieson or orcein

19
Q

What is the study of the identification and distribution of chemical compline’s within and between cells, by means of stains, indicators and microscopy called?

A

Histochemistry

20
Q

Reveals structure in unfixed and unstained (often live) sample by exploiting retardation of light as it passes through specimens

A

Phase contrast microscopy

21
Q

Detects light emitted by UV-illuminated specimens, allowing identification of specific spotters immunolabelled with dyes such as fluorescein

A

Fluorescence microscopy

22
Q

Provides high resolution imaging by passing a high-energy beam of electrons through a very thin section

A

Transmission Electron Microscope (TEM)

23
Q

Scattered light from samples illuminated from the side reveals structure in unstained specimens

A

Dark field

24
Q

A technique used to reveal collagen organisation in picrosirius stained specimens

A

Cross-polar microscopy

25
Routine study of stained sections
Bright-field microscopy
26
Provides high resolution images of surfaces by passing an electron beam across a sample prepared with heavy metals
Scanning electron microscope
27
Uses laser illumination and a pinhole to allow capture of optical sections
Confocal microscopy
28
Exploits interference patterns of refracted light to create an impression of depth in unstained and unfixed specimens
Differential (or Nomarski) interference microscopy
29
When is a smear biopsy used?
Cervix Buccal Cavity
30
When is a curettage biopsy used?
Endometrial lining of uterus
31
When is a needle biopsy used?
Brain Breast Liver Kidney Muscle
32
When is a direct incision biopsy used?
Skin Mouth Larynx
33
When is a endoscopic biopsy used?
Lung Intestine Bladder
34
When is a transvascular biopsy used?
Heart Liver
35
Nissl bodies
Using appropriate stains, the RER and free ribosomes appear as basophilic, granular areas called Nissl bodies These are sites of protein synthesis Are abundant in large nerve cells such as motor neurones
36
Chromatolysis
Refers to the disintegration/ dispersal of Nissl bodies following motor neurone injury
37
Breslow Thickness
Measures depth of melanoma invasion from granular layer of epidermis: Thickness 5-year survival -------------------------------------------------- <1mm 95-100% 1-2mm 80-96% 2.1-4mm 60-75% >4mm 37-50%