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Genes, Cells, Tissue 1 > Histology Wk 1 > Flashcards

Histology Wk 1 Flashcards

1
Q

What is histology

A

The study of tissues of the body

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2
Q

What are the two interacting components of tissues

A

Cells and extra cellular matrix (ecm)

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3
Q

What does the ecm consist of…

A

Many kind of macromolecules which form complex structures such as collagen fibrils

It supports cells

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4
Q

Name the steps for preparation of tissue for study

A

Fixation
Dehydration
Clearing
infiltration
Embedding
Trimming

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5
Q

What is fixation

A

Small pieces of tissue are placed in solutions of chemicals that cross link proteins and inactivate degradative enzymes, which preserve the tissue structure.

Because fixative must fully diffuse through the cell it is cut into small fragments before fixation to facilitate penetration

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6
Q

What is dehydration

A

The tissue is transferred through a series of increasingly concentrated alcohol solutions ending in 100 percent which removes all water

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7
Q

What is clearing

A

Alcohol is removed in organic solvents in which both alcohol and paraffin are miscible

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8
Q

What is infiltration

A

The tissue is then placed into melted paraffin in an oven at 52-60 degrees until it becomes completely infiltrated with this substance

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9
Q

What is embedding

A

The paraffin infiltrated tissue is placed in a small mold with melted paraffin and allowed to harden

Tissues are embedded with plastic resin are also dehydrates in ethanol and then dehydrated in ethanol and infiltrated with plastic solvents that harden when cross linking polymerisers are added

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10
Q

What is trimming

A

The resulting paraffin block is trimmed to expose the tissue for sectioning on a microtome

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11
Q

What is a microtome

A

It is used for sectioning paraffin embedded tissues for light microscopy

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12
Q

What are paraffin section usually cut into

A

3-10 micrometers thickness for light microscopy and less than 1micrometer for electron microscopy

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13
Q

What is the term basophilic

A

Cell components such as nucleus acids with negative negative charge have an affinity for basic dyes

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14
Q

What is the term acidophillic

A

Cationic components such as proteins with many ionized amino groups stain more readily with acidic dyes

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15
Q

Name some acidophilic and basophilic components

A

Basophilic
DNA
Rna
Glycoaminoglycans

Acidophilic
Mitochondria
Secretory granules
Collagen

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16
Q

What is hematoxylin used for

A

Stains dna in the cell nucleus, rna rich portions of the cytoplasm and the matrix of the cartilage producing a dark blue or purple color

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17
Q

What is eosin used for

A

Stains cytoplasmic structures and collagen pink

18
Q

Describe the period acid- Schaffer reaction (PAS)

A

Utilises the hexose rings of polysaccharides and other carbohydrate rich tissue structures and stains such macromolecules purple or magenta

19
Q

What is autoradiography

A

It is a method of localizing newly synthesized macromolecules in cells or tissue sections

20
Q

What are radioactively labeled metabolites

A

Nucleotides
Amino acids
Sugars

21
Q

How are slides with radioactively labeled metabolites produced

A

Slides containing these are coated in a darkroom with photographic emulsion in which silver bromide crystals act as micro detectors of the radiation

Silver bromide crystals are reduced by radiation to produce small black grains of metallic silver either under LM OR TEM which indicate the locate the radio labelled macromolecules in the tissue

22
Q

What is in vitro in cell and tissue culture

A

Live cells can be maintained and studied outside the body in culture

23
Q

What is in vivo in cell and tissue culture

A

Cells are bathed in fluid derived from blood plasma and containing many different molecules required for survival and growth.

24
Q

What is enzyme histochemistry

A

Is a method for localizing cellular structures using specific enzymatic activity present in those structures

25
Q

What are the steps for enzyme histochemistry

A
  1. Tissue sections are immersed in a solution containing the substrate of the enzyme to be localized
  2. The enzyme is allowed to act on its substrate
  3. The section is then put on contact with a marker compound that reacts with a product of the enzymatic action on the substrate
  4. The insoluble structure is visible by light or electron miscroscopy
26
Q

Visualizing specific molecules

A

Labels are fluorescent compounds, radioactive atoms that can be detected with autoradiography

Molecules of peroxidase or other enzymes can be detected with histochemistry

Metal particles can be seen with light and electron microscopy

27
Q

What is immunohistochemsitry

A

A highly specific interaction between macromolecules is that between an antigen and its antibody

To localize and identify many specific proteins

28
Q

What is an advantage of using monoclonal antibodies rather than polyclonal antibodies

A

It can be selected to be highly specific and bind strongly to the protein to be detected

29
Q

What is the method of immunohistochemistry

A

A tissue section that one believes contains the protein of interest is incubated in a solution containing antibody against the protein

The antibody binds specifically to the protein and after a rinse the protein’s location in the tissue can be seen with a light of electron microscope

LOOK AT NOTEBOOK IN GOODNOTES

30
Q

What are the two methods of immunocytochemistry

A

Direct and indirect

31
Q

What is the direct method

A

If the cell or tissue antigen of interest is detected by directly binding a labeled primary antibody specific for that antigen

Fluorescent antibodies bind to the direct target antibody

32
Q

What is the indirect method

A

Uses an unlabelled primary antibody that is detected bound to its antigen with labeled secondary antibodies

33
Q

Why is the indirect method used more widely in research and pathologic tests

A

It is more sensitive with the extra level of antibody binding serving to amplify the visible signal and cheaper

34
Q

What is hybridisation

A

The specific binding between two single strands of nucleus acid, which occurs under appropriate conditions if the strands are complementary

35
Q

What is in situ hybridisation

A

When nucleic acid sequences in solution are applied directly to prepared cells and tissue sections

36
Q

What is in situ hybridisation ideal for

A

Determining if a cell has a specific sequence of dna such as a gene
Identifying the cells containing specific mRNA
Determining the localisation of a gene in a specific chromosome

37
Q

Probes

A

The nucleotide sequence of interest is detected with probes
The probe is obtained by cloning by polymerase chain reaction

38
Q

Why is Sudan black used

A

Lipid soluble

39
Q

What fixative is used in light microscopy

A

37% formaldehyde

40
Q

What fixative is used in EM

A

Glutaraldehyde reacts with the amine groups of proteins

Genes, Cells, Tissue 1 (54 decks)

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