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Histopathology > Definitions > Flashcards

Definitions Flashcards

1
Q

Chromophore

A

A colour bearer, atomic groupings which are required for a stain to work. They make an organic compound coloured.
The more chromophores within a compound, the deeper the colour of the compound.
Eg. Quinonoid, Azo and Nitro groups

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2
Q

Chromogen

A

A substance containing a chromophore

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3
Q

Auxochrome

A 
Ionizing group (gives the dye a net positive charge). It assists the dye to bind to the tissue itself. 
If the auxochrome gives a net positive charge = basic dye/cationic dye.
If the auxochrome gives a net negative charge = acidic dye/anionic dye
Eg. Hydroxyl, methyl and amino groups.

Can also intensify the colour itself.

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4
Q

Modifiers

A

Needed by stains to mediate that dye/tissue interaction.
They will enhance or change the dye colour.
Eg. Eosin B and Y

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5
Q

Leuco compounds

A

Destruction of chromophore and restoration in a subsequent chemical reaction
Eg. Schiff’s reagent.

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6
Q

Basic dye

A

Stains the nucleus. Staining “radical” is on a cation

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7
Q

Acid dye

A

Staining “radical” is on an anion

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8
Q

Direct attachment

A

Stain links directly to tissue.

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9
Q

Basophilic

A

Base loving. Acidic tissue elements (negatively charged) attracted to basic dyes (positively charged)

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10
Q

Acidophilic

A

Acid loving. Basic tissue elements (positively charged) attracted to acidic dyes (negatively charged)

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11
Q

Mordant

A

A substance, typically an inorganic oxide, that combines with a dye or stain and thereby fixes it in a material. A mordant is a metal with a valency of at least two and the bond is a covalent bond (chelation).

Gripping a metal atom by two different bonds has a fanciful similarity to gripping prey with two parts of a claw. (Like a lobster).

The interaction (chelate formed) between the mordant dye and a metal is called a Dye Lake.

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12
Q

Dye Lake

A

The interaction (chelate formed) between the mordant dye (dye with mordant capabilities) and a metal (mordant) is called a Dye Lake.

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13
Q

Differentiation

A 
Removal of excess stain (as in regressive staining). Differentiation agents include:
- Mordants
- Acids
- Oxidising agents.
It controls background staining.
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14
Q

Metachromasia

A

When a dye which looks like one colour but when it binds to tissue it looks a completely different colour. It can stain different parts of tissues different colours based on the tissue composition.
The greater the level of polymerization of the dye, the more pronounced the metachromatic effect.

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15
Q

Microarray

A

One block, loads of cuts going from a very highly positive all the way through to a negative all in one block so you can actually see it going through.

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16
Q

Trapping Agents

A

A trapping agent prevents the escape of dye that has entered the tissue entity.
Eg. in Gram’s stain where iodine is used as a trapping agent to form large aggregates with the crystal violet dye.

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17
Q

Orthochromasia

A

The normal colour of a metachromatic dye.

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18
Q

Trichrome stain

A

Trichrome staining is a histological staining method that uses two or more acid dyes in conjunction with a polyacid
Three different dyes with 3 different size particles will penetrate tissues differently depending on density, chemical affinity and permeability. So you’d be able to dye different tissues differently with a trichrome stain and obtain differentiation without having a long, drawn out process of dying with different dyes.

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19
Q

Mucins

A

Another name for glycoproteins.

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20
Q

Haematogenous pigments

A

Pigments derived from the blood (or one of it’s breakdown products)

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21
Q

Autogenous pigments

A

Pigments derived from other metabolic processes

22
Q

Metaplasia

A

The reversible process of change of a histological cell type due to the presence of an external stimuli. Early stages are reversible but can lead to cancer.

23
Q

Elastin

A

3 types:

  • Oxytalin (fibrillar)
  • Elauni (amorphous)
  • Elastic (mixed)

Assembled into filaments and contain large amounts of simple AAs:

  • Valine
  • Glycine
  • Alanine
  • Proline
24
Q

Fibrin

A

Insoluble fibrillary protein present in repair process post-injury.

25
Q

Reticulin

A

Normal protein produced by fibroblasts. Provides supportive matrix in spleen, liver, bone marrow and lymph node.

26
Q

Amyloid

A

Pathological protein. Only present in diseased state.

Once accumulation of amyloid has started it disrupts the normal functioning of tissues.

27
Q

Pigments

A 
A group of coloured molecules that may be produced naturally by the body or introduced. 
Categorized as:
- Endogenous
- Exogenous
- Artefactual
28
Q

Antigens

A

Antigens are molecules capable of stimulating an immune response

29
Q

Antibodies

A

(immunoglobins) Y-shaped proteins produced by B cells of the immune system in response to exposure to antigens

30
Q

Epitope

A

The part of an antigen molecule to which an antibody attaches itself. (A specific sequence of amino acids on antigen).

31
Q

Polyclonal antibody

A

Antibodies that are secreted by different B cell lineages within the body (whereas monoclonal antibodies come from a single cell lineage) and each can bind to a different epitope on the same antigen.

32
Q

Monoclonal antibody

A

Antibodies that are made by identical immune cells that are all clones of a unique parent cell (and so are immunologically identical) and so will react with the same epitope on the antigen.

33
Q

Hybridoma

A

Lymphocyte cell line fused with myeloma cell line

34
Q

Sentinel nodes

A

The sentinel lymph node is the hypothetical first lymph node or group of nodes draining a cancer. In case of established cancerous dissemination it is postulated that the sentinel lymph node/s is/are the target organs primarily reached by metastasizing cancer cells from the tumor.

35
Q

Affinity

A

The degree to which an epitope binds to its specific antibody binding site.

36
Q

Avidity

A

The overall strength of binding between antibody and antigen

37
Q

Aetiology

A

The cause, set of causes, or manner of causation of a disease or condition.

38
Q

Resolution

A

The smallest distance that can be distinguished between 2 points. So basically it is the ability of optical instruments to produce images that are clearer, finer and sharper. (Whereas magnification is the ability of optical instruments to make an object appear bigger)

39
Q

Numerical aperture

A

The numerical representation of the light-gathering capacity of a lens.

40
Q

Wavelength

A

The distance between successive crests of a wave, especially points in a sound wave or electromagnetic wave.

41
Q

Refractive Index

A

A numerical measure that describes how light propagates through a particular medium

42
Q

Focal Point

A

The point at which a lens brings all of the light passing through to a common focus.

43
Q

Chromatic aberration

A

The inability of a lens to bring light of different wavelengths to a common focal point = fuzzy image.

44
Q

Spherical aberration

A

The inability of a lens to bring light passing through different parts of the lens to a common focus

45
Q

Koehler Illumination

A

Koehler Illumination is a process that provides optimum contrast and resolution by focusing and centring the light path and spreading it evenly over the field of view. Sophisticated and well-equipped microscopes fail to yield quality images because of incorrect use of the light source.

46
Q

Astigmatism

A

A defect in a lens caused by a deviation from spherical curvature, which results in distorted images, as light rays are prevented from meeting at a common focus.

47
Q

Birefringence

A

The ability of a substance to split a ray of light into two components; the ordinary & the extraordinary ray.

48
Q

Thermionically emitted electrons

A

Negatively charged particles produced by heat energy.

49
Q

Name some responsibilities of a lab manager.

A
  • Budget
  • Recruitment
  • Supervision
  • Staff performance reviews
  • CPD (Continued professional development)
  • Rostering
50
Q

Name the responsibility of senior scientists and department heads?

A

Day to day running of the department.

Histopathology (3 decks)

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