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Cell & Tissue Biology > L1: Medical Applications of Tissue Processing > Flashcards

L1: Medical Applications of Tissue Processing Flashcards

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1
Q

Name the steps required, chemical used if applicable and purpose of each step in preparing tissue for light microscopic examination

A
  1. ) Fixation: formalin, gluaraldehyde. Preserves normal tissue architecture after death by fixating, coagulating and/or precipitating proteins.
  2. ) Dehydration: graded series of ethanol (to 100%). Removes water from tissue specimen and replaces with alcohol.
  3. ) Clearing: xylene. Prepares tissue for embedding medium.
  4. ) Embedding: paraffin. Tissue infiltrated with paraffin so that it is hard enough to section
  5. ) Sectioning: tissue cut into section with microtome.
  6. ) Mounting: paraffin section is placed on glass microscope slide
  7. ) Staining: impart contrast to tissue structures for distinguishing under microscope
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2
Q

Define acid and basic dyes. Define acidophilic and basophilic

A
  • Acid dye: chemical with a net negative charge. Acidophilic structures and components of cells possessing net positive charge will have an affinity for acid dyes
  • Basic dye: chemical with a net positive charge. Basophilic structures and components of cells possessing net negative charge will have an affinity for basic dyes
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3
Q

Define metachromasia. Stain used?

A
  • Is a phenomenon in which a given stain imparts different colors to the tissue
  • Stain = toluidine blue
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4
Q

H&E. What has affinity for it? What is the color imparted from this dye? Medical application?

A
  • H&E = hematoxylin, basic (blue) and eosin, acid (pink)
  • RNA, DNA, ribosomes and rER are basophilic and have affinity for hematoxylin
  • Secretory vesicles, sER, lysosomes, mitochondria and type I collagen are acidophilic have affinity for eosin
  • Medical application = coagulative necrosis
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5
Q

Feulgen reaction. What has affinity for it? What is the color imparted from this dye? Medical application?

A
  • Color = magenta (purplish-pink)
  • DNA has affinity for it
  • Medical application = nuclear changes in cancer
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6
Q

Mallory triple. What has affinity for it? What is the color imparted from this dye? Medical application?

A
  • Color: nuclei = red, muscle = red to orange, collagen = blue, hyaline cartilage = blue
  • Nuclei, muscle, collagen and hyaline cartilage have affinity for this dye
  • Medical application = highlighting fibrosis
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7
Q

PAS reaction. What has affinity for it? What is the color imparted from this dye? Medical application?

A
  • PAS = periodic acid Schiff. Color = magenta
  • CHOs (glycogen, glycoproteins) have affinity for this dye
  • Medical application = outlines thickened basement membranes in kidney disease, glycogen storage diseases and in alpha1-antitrypsin deficiency in hepatocytes
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8
Q

Osmic acid. What has affinity for it? What is the color imparted from this dye? Medical application?

A
  • Color = black
  • Lipids have affinity for this dye
  • No specific medical application indicated
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9
Q

Verhoeff. What has affinity for it? What is the color imparted from this dye? Medical application?

A
  • Color = black
  • Elastic fibers have affinity for this dye
  • Medical application = Marfan syndrome
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10
Q

Silver methods. What has affinity for it? What is the color imparted from this dye? Medical application?

A
  • Color = black
  • Intermediate filaments of nerve cells, glial cells and reticular fibers have affinity for this dye
  • No specific medical application indicated
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11
Q

Trypan blue. What has affinity for it? What is the color imparted from this dye? Medical application?

A
  • Color = blue
  • Macrophages have affinity for this dye
  • No specific medical application indicated
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12
Q

Prussian blue. What has affinity for it? What is the color imparted from this dye? Medical application?

A
  • Color = blue
  • Hemosiderin (ferric iron) has affinity for this dye
  • Medical application = excessive iron accumulation in hemochromatosis
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13
Q

Nissl. What has affinity for it? What is the color imparted from this dye? Medical application?

A
  • Color = blue
  • Ribosomes (typically neurologic tissue) have affinity for this dye
  • No specific medical application indicated
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14
Q

Iron hematoxylin. What has affinity for it? What is the color imparted from this dye? Medical application?

A
  • Color = dark blue to black
  • Nuclear elements, chromosomes, mitochondria, centrioles and muscle striation have affinity for this dye
  • No specific medical application indicated
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15
Q

What stain would be indicated to identify extracellular deposits of amyloid?

A
  • Congo red
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16
Q

What is immunocyto/histo-chemistry? Discuss two methods and sensitivity of each? Clinical utility?

A
  • Technique that uses antibody tagged with marker (eg. Fluorophore) directed to specific antigen in tissue
  • Encompasses direct method (antigen conjugates with tagged antibody), which is less sensitive as you have 1:1 conjugation and indirect method (antigen conjugates with more antibodies), which is the more sensitive method
  • Utility: categorization of tumor origin and analysis of cancer markers. Eg. Cytokeratin presence indicates epithelial cell origin.
17
Q

What is a specific cell marker for cells of epithelial origin?

A
  • Cytokeratins
18
Q

What is a specific cell marker for Kaposi sarcoma?

A
  • D2-40 and lymphatic endothelium
19
Q

Markers for breast cancer?

A
  • Estrogen receptors
  • HER2/neu (aka ErbB2) receptors
  • Carcinoembryonic antigen
20
Q

What is in situ hybridization? Clinical utility?

A
  • Use of complementary nucleic acid probes to specifically identify nucleic acid sequence of interest
  • Utility: used to identify cell infected with virus, specific genes on a chromosome, detect amplification of genes
21
Q

Marfan syndrome commonly leads to a thinning of the elastic fiber layer of the aortic valve. What staining technique would you use to identify this layer from a tissue cross-section?

A
  • Verhoeff
22
Q

Difference in utility of frozen vs non-frozen tissue sections?

A
  • Frozen tissue useful when need for urgent diagnosis is urgent (unexpected nodule from surgery, presence of metastasis beyond proposed resection field). Section prepared and evaluated within 10 minutes. Fine detail is lost
23
Q

What is FISH?

A
  • Fluorescent in situ hybridization

Cell & Tissue Biology (18 decks)

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